Some plants are more susceptible to pests and diseases than others. There is nothing more disheartening than discovering that the little buggers – whatever they are – are busy destroying any of them. It’s especially frustrating when they kill edible plants and damage ornamentals you have spent years nursing. Here are some answers to questions many gardeners have.
Questions & Answers About Pests & Diseases
Ants
Ants are an important part of biodiversity in the garden. But often they are a sign of other problems. These are some of the problems gardeners have had.
We have a wisteria growing up on the pillar of part of our front porch. It flowered profusely two seasons ago but last year, when the new leaves were forming, we found it smothered in ants. We used so much insecticide that a lot of leaves were affected. Examining it, I found that ants are on it again. Can you help me to try to prevent the ants from getting on it? What is it that attracts ants to plants?
The presence of many ants on a plant indicates. that scale insects or aphids, plant lice, such as greenfly, have colonized the growth. These two types of insects secrete a honeydew that attracts the ants and, in fact, the ants are responsible to a large degree for the spread of the pest. So, you’ll want to get rid of both the pests and the ants.
Spray your wisteria thoroughly with a light mineral oil. In spraying pay particular attention to those parts of the growth that are in contact with the brick of the pillar, because some insects can escape the insecticide there and thus start their dirty work again next season. Use this mineral oil only in winter, and if the scale reappears in summer, switch to Malathion, which will also control the aphids that tackle leaf buds in spring and new growth throughout summer. There are many remedies on the market for the control of ants, eg. Antblock, and Anticide.
This Liquid Ant Killer here below has some pretty good reviews:
White Ants or Termites
Recently, one of my standard rose trees developed a droop; the buds didn’t open properly and just crooked over on their stems, and now the trees seem to have died completely. Despite taking precautions and disinfecting secateurs, gardening tools, etc, the tree next to it now looks as if it is going the same way.
The trouble may be caused by any one of the following: Termites, ie. white ants, that ring-bark the plants; scale insects; pernicious scale can kill members of the rose family; excessive dryness, strangulation as the plants grow: wire or other ties become too tight and strangle the plant if not loosened; weedkillers; (have you used weedkillers in the garden or have they been used in the vicinity?) rose wilt – this is the most serious of all and, as there is no cure for it, you will have to take out the infected plants and destroy them. Aphids are vectors of virus diseases and you should make every effort to keep your garden clear of this pest.
Aphids
The main picture above shows a plant infested with aphids. They can be a major problem in any garden.
I grow strawberries in my garden. Will you kindly describe the manifestations of the virus disease to which this fruit is subject?
Virus symptoms usually appear in the form of leaf discoloration. The leaves have white or yellow spots, sometimes they are mottled: in other cases, portions of the leaf die, or the leaves may be deformed. Affected plants do not grow well, yield a poor crop of fruit, and do not send out many runners. Virus diseases are usually transmitted by insects, especially aphids. It would be best to pull up the plants and destroy them.
This garden-safe product below should help your aphid problem:
Non-Toxic Remedies for Aphids & Other Pests
Can you give some advice on the control of common garden pests without using poisonous insecticides? Our vegetable garden is troubled with aphids on the brassicas and the usual snails and slugs in the summer months. I believe there are means of exterminating these pests without using preparations that might contaminate the soil and endanger insect and bird life. During the past rainy season, we were inflicted with bad attacks of mildew on the cucurbits, as well as pumpkin fly. Can these also be controlled by non-toxic means?
For aphids on brassicas, water the plants with a solution of liquid seaweed. The aphids do not like the iodine in the seaweed.
For slugs put down cabbage leaves smeared with dripping on the undersides. You can also use half grapefruit and orange skins as traps but you must remember to collect the traps and insects each morning. Sluggo does very little harm to animal life, as it consists of granules that soon disintegrate.
For pumpkin fly, use bait mixing Malathion with brewer’s yeast that does not attract bees. See Below:
Mildew is a fungus and can only be controlled by a fungicide; use a copper one such as Southern Ag Liquid Copper Fungicide. Good cultural practice plays an important part in keeping the garden clear of pests and diseases. Cucurbits are less likely to be attacked by mildew if they are grown in any open sunny position and kept well watered, preferably not over the leaves. Encourage the ladybirds, praying mantis, wasps, and other predators as they are very helpful in keeping down insects.
Every year, soon after the plum trees are covered in leaves and small fruit they are attacked by tiny insects, like snails, that eat holes in the leaves. The trees have not grown more than 4 – 5 in (12 cm) in the past two seasons. After separating and planting my dahlias last season, I found many of the plants covered with black plant lice and some of the foliage grey-green in color. What can I use for aphids on my ranunculus?
The little insects that attack your plum trees are what is known as pear slugs. It is the larvae of the sawfly. As soon as the fruit has been harvested, spray the trees with Sevin spray. During the winter, cultivate lightly under the trees to expose the pupae to the frost and birds.
Dahlias: for aphids, spray the plants with Malathion or water them overhead with liquid seaweed. If the dahlias with the grey-green foliage grow in a rather shady spot, they have mildew and for that spray with Garden Safe Insecticidal Soap Insect Killer. If the plants are in a rather shady place, avoid that site next year, as they are sun lovers.
For aphids, you can spray your ranunculus with Malathion, or use liquid seaweed.
Black Aphids
WHAT CAN I use to get rid of black aphids on rhubarb, Christmas cactus and gazanias, and greenfly on Chaenomeles speciosa? I use the rhubarb leaves to make a good spray for greenfly on roses and Syrian hibiscus. I don’t like using poisons.
Try spraying with a strong jet of soapy water (do not use detergents) or a solution of Epsom salt one tablespoon to 1 gallon (4liters) of water. Are you Sure you are watering your plants sufficiently? Aphids often attack plants that are flagging for want of water.
Woolly Aphids
My fern has tiny white spots on the leaves, and the spots are spreading to all the branches. What can I do?
The tiny white dots on your fern are woolly aphids. Spray the plant with Sevin or a carbaryl product once a week until you have got rid of all the insects. If there are any ants round your plants, get rid of them, as they encourage the aphids.
I have maidenhair ferns in earthenware and plastic containers in my lounge and although they are growing very well, they have developed some disease similar to the cochineal on the prickly pear. They are covered with white spots and eventually the leaf turns brown and decays. The soil in the containers is ordinary garden soil from under trees, and the lounge is north facing and very light. It seems to affect only maidenhair ferns as I also have cyclamen and African violets that have not been affected. The soil of the ferns is kept damp, and they are not in a draft. I have ferns growing in the same soil in the garage and they are free of this disease.
It is not a disease but woolly aphids, a small insect, that is troubling them. Spray the ferns with Sevin (active ingredient carbaryl). On the other container container plants use Cutter Lemon Eucalyptus Insect Repellent. When using an aerosol, hold the can 9ins to 10ins (20 to 25cm) away from the plants.
Fungal Diseases
There are many different types of fungal diseases that attack plants. We don’t always know which type it is, but there are various sprays that you can use to get rid of them.
My cinerarias suffer from wilting and “moth-eaten” leaves. The stems have been eaten through. I can find no sign of any insect and dusting with powder has been to no avail. The plants eventually died. What can I do?
They can be attacked by a number of different fungus diseases. If you are growing them from seed you should spray the seed pans with Dithane. As a precaution, also spray where the plants are to be planted out. If the plants develop mildew, which looks like a fine, greyish-white powder on the leaves, dust them with flowers of sulphur.
Caterpillars and greenfly must be sprayed with Malathion on a bright sunny day, so that the spray does not remain wet on the leaves for too long.
My shrubs are covered with moss, especially my brunfelsia, azaleas and Pride of India. We usually have a wet winter with heavy frost.
Getting rid of it is easier said than done. Scrape off as much as you can with a stiff brush, then spray the plants thoroughly and regularly with a copper-base fungicide. If the branches are overcrowded, thin them out a little to get as much ventilation as possible through them. If your drainage is poor, try to improve it. In summer, keep the foliage as dry as possible, just watering around the base of the plants.
My Florida (couch grass) lawn seems to have contracted the dreaded button disease. Dead clumps all over it. Is there a cure other than ploughing it all up and starting all over again? What is the cause?
I am wondering whether your lawn really has button disease or whether it has not been attacked by some fungus disease. In button disease, that is caused by nematodes, the grass develops little hard “buttons” of grass. If your grass has these, brush or rake them off, then feed and water regularly. Florida lawn (couch grass) is not, as a rule, susceptible to button disease. If the grass has large brown patches of dead grass, then the trouble could be one of the fungi that attack lawns. Remove any loose dead grass and destroy it, then spike the area, treat with Dithane and feed and water the grass. The best remedy for scale is Malathion plus mineral oil at quarter strength.
Black Spot
My rose bushes keep getting black patches on the leaves, then the leaves turn yellow and fall off, leaving me with a completely bare bush. When the new leaves form, the same thing happens again. I spray the bushes regularly every two weeks, but to no avail. Now what?
The black patches are caused by a fungus and the disease is commonly known as black spot. Collect the infected leaves and burn them. After you have pruned the bushes in winter, spray them twice with winter-strength lime sulphur (one cup of lime sulphur to 10 cups water), allowing 7 to 10 days between applications. Give the stems a thorough coverage and spray every 10 days right through summer until the end of August.
You must keep up this spraying programme because once the fungus appears on the plants it is extremely difficult to control. Keeping the beds well mulched with compost helps to keep the bushes clear, as the spores are covered and cannot splash up on to the leaves when it rains or the beds are watered.
I have a few healthy Pride of India (Lagerstroemia speciosa) trees. Every year they are covered with masses of flower buds but, before opening, the buds are covered with a fungus or mildew and the flowers do not open and just die down. I sprayed them with lime sulphur, but to no avail.
Spray the trees with Spectracide Immunox, starting when the buds are quite small and spraying once a fortnight. In winter, spray twice with winter strength lime sulphur, covering all the branches very thoroughly. Although Pride of India can stand quite a bit of drought, the plants should be watered when they are coming into flower: give the trees a good soaking two or three times a month if there is no rain.
Fairy Ring
My kikuyu lawn is beautiful, but in two spots the so-called “fairy rings” appear. It is a fungus that lives on the roots of the grass in the form of a circle, about 15 feet (4,50m) in diameter. On the outer edge of the circle, white toadstools appear on the grass. We treated it with a funglcide, but no response. It now seems as if the grass in the inside of the circle is dying.
Fairy ring is caused by a fungus, Marasmius creades and, as it grows deep in the soil, it is extremely difficult to get rid of. Where the soil is infested with the mycelium, it becomes impervious to water, and the grass dies in circles.
To stop the grass from dying. it is essential to aerate it, using a hollow tine fork or an ordinary garden fork: this will allow the water to penetrate. Water the affected rings with Bordeaux mixture. Keep the grass growing well by feeding it regularly with a balanced fertilizer such as 2:3:2 at the rate of about 2 oz. per 10-11 square feet (56g per square meter) once a month. Watering also plays an important part in the control of fungi. Water thoroughly once or twice a week, doing this in the morning so that the grass has time to dry before nightfall. In autumn, and again in early spring when you scarify the lawn, aerate the patches that have been affected by fairy ring and saturate with the Bordeaux mixture.
Damping Off
How can I prevent my gloxinia seedlings from damping off? They were sown in a mixture of peat and loam, but they still damp off.
Damping off is caused by a fungus and I suggest you use the Pro mix or John Innes soil mixture (depending on your country) for your gloxinia seed. This is made up of two parts loam, one part peat and one part clean coarse sand. Sterilize this either by steaming for 20 minutes or baking in the oven. To every standard apple-box of this mixture add 1½ ounces (42,5 g) super phosphate and 0.7 ounces (21 g) agricultural lime. Water the ground with Dithane, a heaped teaspoonful to 9½ pints (4,5 liters) water, before you sow the seed and, if you notice any seedlings damping off, repeat the treatment. Sowing the seed very sparsely also helps to prevent damping off.
Fusarium Wilt
My dianthus plants appear to be vigorous and healthy and on the point of blooming, when they suddenly wilt and die. The bed has been well prepared and fertilized with cow manure fertilizers and kept watered.
They have “wilt”, caused by the fungus, fusarium. The disease is worse in midsummer and can be caused by overwater, especially in poorly drained soil. Dianthus grow best in well drained, slightly alkaline soil. Water the plants with a copper spray three or four times and repeat in two weeks to try to prevent the disease from spreading, and do not overwater.
Sooty Mold
I have a gardenia that blooms every year but, since blooming this season, I have noticed that it is full of black fungus. What should I do? Cut it down or just cut off the infected parts?
Your garden is suffering from sooty mold, a black sooty growth that really does not harm the plants. This fungus lives on honeydew, a sweet secretion of aphids and scale, both of which ants encourage, as they feed on the honeydew. Spray the bush with Malathion: this will get rid of the aphids and the mould will soon clear up. Try to get rid of the ants too.
Rust
Rust diseases are caused by a fungal parasite that lives off plants. There are many different types of rust disease.
The undersides of many of the leaves of my mint are covered with a number of small brown spots, some about the size of a pinhead, that could be some kind of fungus or the spores of some pest. I frequently cut the mint down to ground level, but the spots reappear on the next crop. Is this common with mint, and what causes it?
These spots are caused by rust – which is a fungus. It is difficult to get rid of rust on mint and I suggest you start a new bed in a different part of the garden, using fresh, unaffected plants. You can try dusting the new bed with sulphur, that is quite harmless, to prevent the rust returning.
My geraniums have rust. What can I do?
Rust is a fungus disease. Dithane is the remedy, but rust is difficult to get rid of once the plants have become infected. Pick off as many of the lower infected leaves as you can and burn them, then spray with Dithane every week, paying particular attention to the undersides of the leaves. Rust is usually worse during wet weather – so try to keep the plants quite dry.
My snapdragon plants have a brown spot on the back of the leaves that appears to be a fungus. The plants are grown in a bed with very good compost and they get watered about twice a week.
They have rust, that is caused by a fungus. Spray the plants thoroughly, paying special attention to the undersides of the leaves, once a week with Dithane. Do not put infected plants on the compost heap, but destroy them. If you grow snapdragons next season, plant in a new site.
Carnation Rust
I have been growing American tree carnations quite successfully in cement pots for the past four years and now rust spot has developed in the stems and leaves?
Your flowers are suffering from carnation rust that can be controlled by thorough weekly sprayings with Dithane. A pressure-type sprayer is recommended for applying the chemical. Destroy all drying and old plants. Give your carnations full sun, with free circulation of air. If watering overhead, water during the day so that the foliage is dry by nightfall.
Mites
Mites are tiny, spider-like creates that cause lots of damage in the garden. For this reason, they are referred to as spider mites.
Cyclamen Mite
During the first season of growth, my cylamen plants were healthy and flowered. After resting, I started watering them and they produced buds. Half the buds went dry and the leaves turned yellow. I stopped watering and the plants died completely. At the moment the plants are full of buds but have very few leaves.
Your plant may be suffering from an attack of cyclamen mite and I suggest you give them one application of a systemic insecticide such as BioAdvanced Insect Control. Mix these according to the directions on the container, and water a little around the sides of the pots. When the leaves start turning yellow, gradually reduce the water supply, during the summer, keep them on the dry side, but never completely bone-dry. Next autumn, start watering them again, giving them a little at first, then gradually more water as they come into growth.
Always water around the rim of the pot, never over the tuber, and do not overwater. The way to test whether the plants need water is to tap the pot: if it rings hollow, it needs water. If the sound is dull, do not water. Cyclamens like a fairly cool atmosphere and plenty of light but not direct sunlight.
Beetles
My grape vines look very healthy, with nice bunches of grapes, but the leaves are being eaten by something. How often do l water them and is there a special feed?
The leaves of your grapevine are being eaten by the June beetles aka June bugs, or May beetles, that come out at night. I have found that the only remedy is to go out at night and catch the beetles by hand. Give the vines an application of 2:3:2 fertilizer, say about half a jam tin, spread well out around each plant, and about 4 ounces (113 g) magnesium sulphate in spring. Water from late summer, a thorough soaking about twice a month, until the regular rains start.
Borers
Borers are a group of insect pests that feed inside the roots and branches of trees and other plants. They can do a lot of damage.
Corn Borer
During the last two seasons, my dahlias have been attacked by a grub that eats away the flower head. The flower blooms on one side only, and when the head is opened up one finds two or three small brown or cream colored grubs about ¼ in (6 mm) long at the base of the flower head.
It could be the corn borer, that attacks dahlias. Destroy infected blooms and next year spray the plants with either a systemic insecticide such as Rogor CE, about every three weeks, or use Sevin once a week. When you cut down the plants at the end of the season, burn all the old stems.
Stem Borer
This season my rose bushes are in a fine healthy condition, with no sign of disease. The only pest that worries me is the stem borer – a small fly that bores down the centre of the stalk and removes the pith. After I’ve cut off a rose stem, this fly is busy on the job within minutes. I have tried several remedies, including a dab of paint of black bitumen. Is there a good way of controlling this fly?
The borer that makes holes in the rose stems is a small carpenter bee; it does some good in the garden as it catches insects and puts them in the stems for its young to feed on when they hatch. Mix 300cc motor oil, one teaspoon copper spray powder, and two teaspoons wettable Sevin, well shaken and kept in a bottle. Put this on the stems immediately after cutting the blooms. My remedy is to cut a small piece of stem and push this into the hole to prevent water getting in, and I seldom find the stems dying back.
Millepedes
My garden is infested with millepedes. How can I get rid of these pests?
Millepedes are harmful to plants, often doing a great deal of damage to root crops such as potatoes, carrots, beetroot and turnips. The infestations seem to come in cycles: the population builds up and then disappears.
Finely powdered naphthalene forked or raked into the ground before planting, at the rate of 4 ounces (113 g) per square metre, or lightly forked in around cultivated plants, is a useful remedy. The millepedes can also be trapped by burying pieces of potato or carrot just below the surface of the soil. Pierce each piece of vegetable with a small stick to mark the spot where it has been buried, so that you can collect the millepedes the next morning.
Worms
There are good worms and bad worms that harm – sometimes destroy – plants.
Earthworms
I HAVE noticed a large number of smallish earthworms in my container plants and have been told that, although they are beneficial in open soil, they are fatal in confined space such as a container. If this is correct, please could you tell me how to rid the containers of these earthworms? I sterilize the soil before planting, but all the containers stand on the riversand floor of my potting shed.
There are two opposing opinions about whether the worms harm container plants or not. Of course, they do not feed on the roots of the plants but are a nuisance because they clog the drainage holes. One way to get rid of them is to water the pots with limewater, but be careful: this would injure acid loving plants.
Another method is to drown the worms by standing the pots in water for some time. If you leave the pots on the sandy floor of your potting shed, you will have to make up your mind to put up with the earthworms: they will just reenter the pots as soon as they are returned to the floor and the effect of any treatment has worn off.
Sod Webworms
Our couch grass lawn used to be beautiful. But over the last five years it has become riddled with what I was told are “web-weaving ground worms.” These pests started by destroying a 20-foot (6-meter) circular bank of mesembryanthemums and then invaded the lawn. Spraying seemed to have little effect. Now the lawn is almost non-existent, except in the larger open spaces between the trees. Could the vast amount of tiny acacia leaves dropped every winter be the real trouble? Or is it a combination of not enough sun, leaves, and worms?
The worms are known as sod webworms. Spray the grass with any preparation containing carbaryl, eg, Sevin. As there are several generations of this pest during the season, you will have to repeat the application from time to time until the lawn is free of worms.
The caveat is that leaves dropping on the lawn will have a bad effect and they will also make the soil acid. I suggest you brush away all the leaves and give the whole area a light application of agricultural lime, just sufficient to make it white. About a month after that, start feeding the grass, applying BioAdvanced triple action fertilizer 2:3:2 at the rate of 3oz (85g) for 10 sq ft (1 sq m) once a month until early fall. Apply the fertilizer when the grass is dry and water in immediately afterwards.
The following summer, start your feeding programme in early fall, keep a careful watch for the return of the sod webworms and spray immediately if you notice any.
Fruit Fly Maggots
For some years now I have noticed that my fruit, peaches, in particular, have been infested with worms. The fruit appears perfect on the outside but the inside, around the pip, is completely infested with small white worms. This used to affect only the later fruit, but this season I noticed that all the fruit have been affected.
These worms are the maggots of the fruit fly. The remedy is Demon Max Insecticide (active ingredient of last two is Cypermethrin). As the fly is stinging the fruit earlier, one will have to start spraying earlier. Read the directions on the bottle very carefully and make a special note of how long must elapse between the last application of spray and harvesting the fruit.
The flies winter in hedges and evergreens, coming out on warm sunny days to feed on sweet liquid and it pays to put out bait for them during winter. A good bait can be made up as follows: water 4.5 gal (18 liters) white sugar, 3 lbs (1,36 kg). Trichlorfon 50% wettable powder. Splash this over the leaves in big drops. Always destroy infested fruits. Soak in water with a little paraffin on top for a few hours, then bury.
White Fly
Several diminutive moths infested my geraniums. When you touch the plants these insects rise in a cloud, and I think they are of a sucking variety. They infested only my geraniums last year, but the problem is more serious this year. My fuchsias are also infested. Leaves turn brown and drop off and the plants look very sick. I have tried Malathion, with no visible effect.
The moths on your plants are white fly. It is a minute fly with body and wings covered with a fine white powder that makes it difficult to control. The latest remedy for white fly is Phenothrin, also called sumithrin and d-phenothrin,[2] is a synthetic pyrethroid that kills adult fleas and ticks When using an aerosol, hold the can 10 to 12 inches (20 to 25cm) away from the plants and try to spray under the leaves, for that is where the insects settle. The flies breed in winter and clean culture during the winter months helps to keep the pest under control.
Weeds
Some weeds are more troublesome than other sorts.
Onion Weed
We recently bought a property in town and it is overrun in weeds, parts of which look like a small onion. The white flower is and at the bottom of the bulb there isa mass of small bulbs. They look like grape seeds. It is also in the kikuyu lawn.
It is commonly known as onion weed, the botanical name is Nothoscordum inodorum. It originates from North America and is now a very troublesome weed in many countries. There is no weedkiller you can use that will not harm your other plants as well. Someone told me that if you put a drop of paraffin in the crown of each plant this will kill it. One way of getting rid of the weed is by persistently weeding it out, paying special attention to the tiny plants as they come up, and never letting any plant go to seed.
Oxalis
The culprit in my garden is oxalis with the mauve flower and bulblet. Part of the garden is overrun with this weed; you can dig and sieve, but it still appears. Is there any effective spray that can be used that will not affect the soil or adjacent plants? Also, our lawn, has developed yellow patches here and there. We have applied ammonium sulphate, but the patches still persist.
If you use weedkiller on this weed, you will kill plants in the vicinity. You can get rid of it by persistent weeding, but you must not put the bulbs on the compost heap. If you do, you will just reinfest your garden. I know this is hard work but it can be done. I have cleared my garden of it by going over the beds again and again. The yellow patches in your grass could be caused by fungus. Rake any dead grass off, aerate the patches, water with Bordeaux mixture (a tablespoon to 10 pints (4,5 liters) water) then feed.
Daisy Fly
Our Barberton daisies open with only some of the petals formed and others missing, although the plants and leaves look healthy. Another disappointment is the carnations. We have a lovely one in a cyclamen pink that turns mauve when the blooms fade. The stems seem too weak to support the blooms, so they all drop.
The Barberton daisy fly causes the trouble in your daisy blooms. Sprays do not seem to have much effect on this pest and the recommended remedy is putting out Malathion and sugar bait. Mix two heaped teaspoons of wettable Malathion powder with 12 ounces (340 g) of sugar in 9½ pints (4,5 liters) water. Stir well and splash this on the foliage in large drops once or twice a week. It sounds as though you have wilt in your carnations. Pull up infected plants and destroy them. Start a new bed in a different part of the garden and make sure the soil is well drained. If you have healthy plants of your pink variety, take cuttings from those, but do not take cuttings from unhealthy plants
Scale
Scale insects are small bugs that multiply and suck the life out of plants.
We are continually planting tea bushes just to lose them when they are quite large to some disease that turns them completely black with small white spots. With what shall I spray when this virus appears?
The trouble is caused by a scale insect and is not a disease or a virus. I have found Malathion plus mineral oil at quarter strength is effective against this scale, but you must spray every 7 to 10 days until you have got rid of it all and then you must watch that it does not return, as it is a persistent insect. It also helps if you treat the plants correctly, giving them well drained acid soil, keeping them watered throughout the year, and never digging round them: they resent root disturbance.
What should I do about a scale pest all over the bottom of my beautiful jasmine? Last season, I rubbed the stems with meths and it recovered, but the scale is back again this year.
Perhaps scale attacks your jasmine because you do not water it regularly. Scale often attacks plants in poorly ventilated places such as a hot dry corner.
My mango tree has been attacked by scale. How can I get rid of it?
Spray the tree with Malathion plus mineral oil once a fortnight until the trouble clears up. Try to spray underneath the leaves as well as on top. Make a careful note of the time that elapses between the last application of spray and picking the fruit.
Powdery Mildew
My ranunculus grew beautifully, but the foliage turned white. I also found this on some of my dahlias. I have burned all the ranunculus bulbs. Must I destroy my dahlia bulbs too, or can I spray them?
Your ranunculus was attacked by mildew. If your dahlias are also covered in a grey-white powdery substance, then this is mildew as well. Spray the plants with Spectracide Immunox. Keep them well watered, but try not to wet the foliage.
Moss
We have two rockeries on our lawns that have been planted with succulents and cacti. Sand was used as we thought, in view of our heavy winter rains, this would drain better. Now, after four years, green moss is appearing all over and my plants are very poor. Some have actually rotted.
Scrape the moss away and put down a mulch of crushed charcoal. Where plants have died, take the soil out of the pockets and replace with sandy soil mixed with some compost and charcoal, and put down a mulch of crushed charcoal over the soil when you replant.
Slugs
After more than 20 years of gardening under various circumstances, I felt I knew practically all the answers. Then the garden was invaded by slugs. Having tried every available means of attack, from branded baits to the home made Meta/corn meal method, and after having lost my fourth batch of seedlings, I finally capitulated.
Would that I could give you a perfect remedy for getting rid of slugs. Here are various remedies used by other gardeners. Ducks and/or bantams but the latter do tend to scratch up the plants.
Traps: rub the undersides of cabbage leaves with dripping and place these, dripping-side down among the plants, collecting the “catch” next morning, or use half an orange or grapefruit shells as traps. Sometimes a little trail of dry sand around the plants or beds will discourage the slugs: they do not like crawling over dry ground. Some people also use salt, but one has to be careful about using too much of this in the garden some plants are sensitive to sodium in the soil.
Mushrooms
My problem is mushrooms on the lawn. I pick all the cups the moment they appear, and have treated the spots with copper sulphate and copper oxychloride over long periods, but to no avail. The mushrooms come up in their hundreds in the same places and are also spreading in all directions. The lawn is deteriorating in these parts.
I suggest you follow this programme. Scarify the lawn, taking off all the old grass, that provides a good growing medium for the mushrooms. Next aerate the grass with a hollow-tine fork and feed once a month with 2:3:2 at the rate of 60g per square metre. Treat once a week with Bordeaux mixture until the mushrooms disappear.
My geraniums are prone to stem rot and, also, the leaves turn yellow and fall off. What can I add to the soil, that is sandy, to give vigour to the plants?
For stem rot, drench the soil round the plants with a copper spray and do not overwater them. Improve the texture of your soil by adding humus.
My African violets developed a kind of disease that seems to spread from one plant to another. It is like fine salt sprinkled on the flowers and leaves. Even the stems are white.
It sounds as though they have mildew, that is a fungus disease. The remedy is to dust the plants with sulphur.
I HAVE noticed that the majority of my rosebuds are infested with moth eggs. What ettective spray could be used to kill the eggs? At present I am just squashing them with my fingers.
They are probably the eggs of the bollworm. When the little worms hatch, they burrow into the rose, making it look as though pierced with a needle. You can get rid of a lot of eggs by squashing them with your fingers, but you can also kill the little worms by spraying the plants with Sevin paying particular attention to the buds.
MY LIME TREES develop lots of leaves, but no fruit. The leaves have got little bumps on them. For the last two summers I have had thousands of mole crickets in the lawn. I have tried detergents but I’m afraid this will destroy the soil in the long run.
The little lumps on your lime leaves are caused by citrus psylla, a small insect that in itself does not harm the trees except to make the leaves unsightly, but it is the vector of greening disease. Spray the tree with a systemic insecticide such as Rogor, taking particular note of the time that must elapse between the last application and picking the fruit. Give the tree about ½ lb (250g) of 2:3:2, spread out evenly from within a few centimetres of the trunk out to the drip of the branches; put down a generous mulch of compost and water thoroughly about every three weeks. This treament might induce it to fruit. For mole crickets spray the lawn in the late afternoon with Sevin
WITH WHAT can I spray my vines against downy mildew? This year I am using Immunox. I have used copper oxychloride, and lime sulphur: nothing has helped. Some of the vines are in the open, some facing east and south east.
A Liquid Copper Fungicide should control the mildew, but the most effective and cheapest remedy is sulphur, Bonide Sulfur Plant Fungicide, is one product. Dust the vines with dusting sulphur. Give the first application when the new shoots are 10cm long, the second immediately after the vines have flowered and the last one when the berries have reached the size of a pea. In winter, give the vines two thorough applications of lime sulphur mixed at the rate of one cup lime sulphur to eight cups water. Spray the ground under the vines as well.
An azalea bush in my garden is very happy where it is growing; it flowers every season and, from a distance, looks healthy. During the last flowering season, when I went to pick a few sprays, I noticed odd hard knobs growing out of the ends of some leaves. I pulled them off, threw them into the dustbin and no thought more of it. Recently the disease has become noticeably worse.
Your azalea has what is known as leaf gall or azalea apple. You were right in picking off infected leaves, but you cannot go on doing this, so spray the bush with copper oxychloride about once a week until the trouble clears up. Watch that particular bush and, if the trouble recurs, spray again. Some varieties are more susceptible than others and the trouble is usually worse during wet seasons.
My agapnathus leaves have become covered with a white substance and, in some cases, are speckled. Growth has been retarded and flowers are underdeveloped. This disease is spreading to adjoining agapanthus plants that have become stunted, and there is a danger I will lose them all.
The red-hot pokers’ leaves are covered with a black substance, plants and flowers are adversely affected and flowers have started to droop. Should badly affected plants be removed if there is the danger of these diseases spreading to the rest of the garden?
Your agapanthus have been attacked by mealybug. Spray the plants thoroughly once a week with Malathion until the insects are under control. Clean up the plants, removing some of the older badly infested leaves. Give the plants some general fertilizer and keep them well watered to improve their general condition.
Red hot pokers have been attacked by a fungus. Spray with copper oxychloride once a week. If the plants have been growing in the same place for a number of years, I suggest you move them to a new site.
My lawn is a fine grass, magennis, but it has started developing dead patches. Initially, an area turns a mauve shade and then rapidly dies and turns yellow. After a time this yellow patch gets green shoots and again slowly regains its original health.
Your lawn is suffering from brown patch disease, that is common when grass is overfed with nitrogen. This causes soft growth that easily falls prey to diseases. The following control measures are recommended: brush with a hard broom to remove “thatch” dead grass blades. This operation is normally done in spring. Use a grassbox on the mower to prevent thatch developing. If the lawn is watered, let it be a weekly soaking rather than a sprinkling every few days. Give the whole lawn an application of superphosphate at the rate of a handful each 10 sq ft (1sq metre). Use a 2:3:2 fertilizer mix to ensure a balanced feed, but reduce the amount of nitrogen. If the trouble persists, treat the lawn with a copper oxychloride spray.
THE LEAVES of my strawberry plants have brown spots on them. These spots seems to spread until they cover the leaf. Then this travels down the stem and the leaf becomes brittle and dies. I spray with Dithane. This does not seem to help. If I leave the plants after they’ve collapsed, they sometimes send up a new shoot and start again.
The trouble, known as leaf spot, is caused by a fungus. As you say Dithane has not had any effect, use copper oxychloride. Start spraying early spring; stop when the fruit is getting ripe and resume after it has been harvested. Spray about once a week. Clean up infected leaves and destroy them. If you start a new bed, make this in a new site well away from the old one.
IS THERE anything one can do about rose beetles? They have destroyed a lot of my plants this year.
The only effective way I have found of dealing with the rose beetles is to go out at night with a light and çatch the insects when they are feeding. They start coming out in June and continue until about the end of September. Spray the bushes in the late afternoon with Sevin (active ingredient carbaryl). To every 10 pints (4,5l) of spray add 10ml (two teaspoons) of Lysol to make the effect of the spray last longer. If you hunt them consistently year after year, you can reduce the population so that it does very little damage. When digging, destroy their grubs, commonly called white worms. These are greyish white worms with six legs just behind the brown head. They range in size from a 1/4in to 1in (5mm to as much as 2cm), depending on age, and are usually curled up like the letter C. When you go out hunting for the beetles, look at grape vines, arums, beans, fuchsias, hollyhocks, roses, copper beech trees and apricot trees.
I HAVE been growing my own plants in seed boxes in sterilized soil. Suddenly my seedlings were being eaten one by one. The plants would be chewed down to about ½ in (12mm) from a soil level. At this stage I had all the seed boxes raised on a table about a meter from ground level. I scratched around in the soil but found nothing. I moved all the boxes to another part of the garden, to no avail.
Next time you want to look for cutworms in your seed pans, do not scratch around the soil (this disturbs the roots of the small plants), but flood them with water: the worms will come up for air and you can catch them. Did you look under the pans for slugs? Slugs can often cause a great deal of damage and, as they crawl under the pans during the day, their presence is not suspected. Caterpillars could also be the trouble: if you grow more seedlings and they’re eaten, spray the pans with Sevin. Birds could also be nibbling the seedlings off, especially as the pans were placed quite high.
SOME OF my salpiglossis plants have simply keeled over and died. On examination of the root system I discovered microscopic worms.
They were attacked by fungus and the minute white insects on the roots had nothing to do with their dying, but only arrived after the plants had died. There is little you can do about this trouble except to plant in very well drained soil, or even on ridges, so that the water drains rapidly away from the base of the stems. Never overwater the plants, and try to grow them in a fresh site each year.
I HAVE two gloxinia plants that look healthy enough. The buds appear looking strong and healthy, but when they reach the point when they should turn into lovely flowers, they just wilt and die.
Your gloxinias probably have what is known as bud blast, that may be caused by any one of the following: too much fertilizer, too much water, not sufficient humidity, watering with cold water, or thrips. To increase the humidity, place the pots in a shallow basin with a layer of pebbles or chipped stone at the bottom and just suffucient water to come below the base of the pots, so that they do not stand in the water. The other symptoms of attack by thrips are that the tips of the leaves wither, the stems look rusty and the undersides of the leaves may be spotted silver brown. If thrips are suspected, spray Ortho Max or Malathion or dust with sulphur.
ONE DAY my plants are blooming and in full health, the next the leaves start to wilt and the plant dies. I haven’t found any insects, but I have noticed that the stems of the plants are hollow inside. This is happening all over the garden, even in my window boxes.
The plants are suffering from what is known as wilt. There is little you can do about it except take preventive measures. Pull all infected plants up and, if possible, burn them. Do not put them on the compost heap. Do not plant asters and petunias where you have been growing them this season. You can try disinfecting your soil with Jeyes fluid. Dig the ground over and saturate with a solution of Jeyes fluid – one tablespoon of Jeyes fluid to 4,5l water, and use at the rate of 9l per square metre. If possible, cover the soil with polythene or sacking for a week. Remove cover, and fork over ground again and leave for another week before planting. Make sure your ground is well drained and never overwater the plants.
LAST SEASON we had a very large crop of passion fruit but portions of many of them were a hardened mass, particularly towards the end of the season. This season I have had two crops, the first one a small crop, but producing exceptionally large, though sour fruit. The present crop is more abundant than last year’s, but few of the fruits grow big, many falling off rather small and too green. I gave them some 2:3:2. The skins are full of brownish spots
The hardened scale mass on the passion fruits is caused by a virus and is known as woodiness or bullet disease and there Is little you can do about it The virus has less effect on plants that are growing luxuriantly and are kept well fed. The virus is probably also responsible for the small green fruits. Give the vine a dressing of the fertilizer mixture 3:1:5, about 8 to 10oz (250g) spread out over the root area and a generous mulch of compost and water thoroughly and regularly. The extra potash in this fertilizer mixture should improve the flavour of the fruits and make them less acid. You can try spraying the plant with Bordeaux mixture or copper oxychloride for the brown spots
WHAT CAN I use to control red spider on my African violets?
Red spidercide. Use the dilution recommended on the container and apply about once every three weeks until the infestation clears up.
MY PEACH TREES, both old and young, have gum oozing through the bark and this seems to do them quite a lot of harm.
Your trees are suffering from what is known as gummosis. The remedy is to spray with a copper spray in autumn when the leaves begin to fall, and again in spring immediately before buds burst; make sure the trunks and branches of the trees are thoroughly covered. Give the trees a dressing of general fertilizer 3:1:5 in August, about 18oz (500g) to a mature tree and 10oz (300g) to a young tree, and 8 ½ oz (250g) of magnesium sulphate and some trace element mixture, the amount according to directions on the container. Then put down a mulch of compost. The general health and vigour of the trees play a part in keeping gummosis away. About six weeks after giving the trees the fertilizer, give them a light dressing of lime, just enough to make the ground white.
WHAT IS the cause of a growth on the back of Barberton daisy leaves? Is it a fungus or an insect?
The trouble is caused by a fungus and the remedy is to spray with a copper spray every two weeks until the trouble has cleared up. Try not to overwater the plants.
I HAVE recently taken to growing fuchsias. The leaves of my plants (the plants vary in age from newly potted plants of about two to three months to those that were potted about six months ago) wither, become brittle and fall off. Sometimes the leaves just show signs of wilting and then the plant appears so far gone that it does not respond to watering. I have noticed that the stems are hollow, even to root level.
It sounds as though the trouble is plant dieback that is caused by several organisms and that is worse when the soil is badly drained. Make sure your pots are really well drained and never over water the plants. Remove infected stems to clean healthy wood. If dieback is a problem, prune out dead or dying branches and remove them from the site. Disinfect the pruning tool between cuts using 10% household bleach, 70% alcohol, or a disinfectant product. If bleach is used, rinse to prevent rust. A good time to prune is late in the dormant season for many plants. For spring flowering trees and shrubs, wait until after flowering to avoid removing flower buds. Burn the affected wood you have cut off.
MY KIKUYU lawn has large rings where it is dying out. The grass goes yellow round the edges and moves out in an increasing circle. The inside circle fills with weeds and weak bits of lawn.
It has been attacked by a fungus, probably fairy ring. Dig the weeds out of the patches, aerate the area well, then saturate with a fungicide such as Spectracide. After that, fertilize the patch and wait for the grass to grow again. In autumn give the whole lawn a thorough soaking with Bordeaux mixture.
HOW CAN we control white ants in our lawn, fruit-trees, shrubs and vegetable garden?
You can use any of the pesticides on the market that have carbaryl in them. Scatter around the holes where the termites are active, repeat two to four days later, and again 10 days later if they are still active. Chop grass into short pieces, dip into a solution and scatter round the holes.
HOW DOES one get rid of a fig borer?
Once the borer has attacked the trees, it is not easy to get rid of it. There are two things you can do: push a piece of fine wire down the hole(s) and try to kill the borer, or force linseed oil down into the burrows. Once you have got rid of the borers, protect the stems by placing a sleeve of fine wire gauze around the trunk, starting about 6ins (15cm) away from the base and reaching up to a height of 2 ft (60cm) where it should be firmly tied. The female borer only lays her eggs near the ground, usually not more than 2 ft (60cm) above ground level.
MY LEMON TREE is a young tree, about 18 months old, and the trunk has split right down showing the inner core. Its leaves are yellow and the whole tree is generally unhealthy. It is well watered and tended, but the soil here is very stony and full of mica.
It sounds as though it has what is known as collar rot. Treat it as follows: expose the infected area by removing the soil from the base of the stem and the first roots. Cut away infected wood and discoloured bark until ½ to ¾ in (10 to 20mm) of healthy bark has been removed from around the infected area. Sterilize your knife in one part Chlorox to nine parts water, before and after use.
Cover the wound with a paste made of copper oxychloride powder and water. Make sure no water collects around the collar of the tree and, when the wound has callused, paint it with a pruning sealer. Give the tree some fertilizer to encourage it to recover, and keep it mulched with compost, but do not put this too near the trunk. Destroy all the shavings that you remove from the tree.
BLACK AND red blotches have recently appeared on the leaves of my hibiscus trees. They appear on both young and old leaves that, after a time, turn yellow and fall off. At first, I put it down to a mineral deficiency and applied small quantities of 2:3:2 with a fortnightly Miracle-Gro foliar feed. I have now come to the conclusion that it could be a fungal disease.
The trouble could be caused by a fungus and you can spray with Dithane. If, after some weeks, this does not seem to be having any effect, try Spectracide. I suggest you give each tree 50g magnesium sulphate and an application of trace element mixture at the rate recommended on the container. It may take from six to eight weeks for the magnesium sulphate and trace elements to have any noticeable effect.
MY FUCHSIAS have fine red powdery spots on the underside of the leaves. Round this powder the leaf dies and drops off. The fuchsias are planted in hanging baskets lined with pine needles and are well watered. They get only morning sun
Your fuchsias have fuchsia rust, that is a fungal disease, and you must spray them with Dithane. Remove as many infected leaves as you can and burn them before spraying the plants thoroughly, covering both the upper and lower sides of the leaves. When you have got rid of the rust, spray the plants with copper oxychloride from time to time, especially during wet and humid weather.
HOW CAN I get rid of the large black and yellow beetles that have played havoc in my garden this season and devoured the roses?
Here are several remedies you can try. Place yellow buckets and/or dishes with water in them among the bushes. It is said that the beetles are attracted by the color and drown in the water. The other remedy is to squash a few of the beetles and put the corpses on the rose bushes. The person who gave me this remedy says it is infallible. The beetles breed in compost and decaying vegetable matter, so clean up under hedges and in other corners where leaves collect. Spray the bushes with Sevin and to every 10 pints (4,5l) of spray add 2 US teaspoons (10 ml) of either Lysol. There is also a new Spectracide Bag-A-Bug available.
WE HAVE two orange trees in the garden, one bearing ripe fruit from early September and the other tree ripening in March. More than half the crop turns mouldy and drops. Even the sound fruit we bring indoors often goes mouldy after a few days.
Spray the trees thoroughly once at 100 percent petal drop with Bonide. Then spray with copper oxychloride three weeks before harvesting, covering the tree, fruit, trunk and ground under the tree thoroughly. The safety period for both these fungicides is 14 days. If the trouble persists during the rainy weather, spray again but be careful to allow the necessary safety period. If any of the branches are touching the ground, either prop them up or trim off a few of the lowest ones. The infection splashes up from the ground. I suggest you try to get some 2:3:2 zinc and give that to all your citrus trees when you fertilize them. Mulch the ground under the trees with compost as well.
FOR SOME time my amaryllis have been infested with a caterpillar that burrows into the leaves. We have repeatedly sprayed with a worm spray that has had virtually no effect.
They are known as the amaryllis or lily worm and the worm spray should be effective as it contains carbaryl. I have used Neem oil with great success. Ortho Insect Killer Flower & Vegetable Garden Dust kills insects for up to 8 months.
MY WALNUT TREE is mature and has borne regularly for many years. But this year the nuts are badly infested with codling moth and the outer coverings have turned black.
Wondercide should control the codling moth. Start spraying when the nuts are about the size of a lentil and repeat every 10 days until the shells have hardened. You can also use bait, either splashing it on the leaves in large drops once a week or hanging little pots of it in the trees. You can make up a bait as follows: ½ oz (15g) Malathion wettable powder, 12 oz (350g) sugar and 10 pints (5l) water. The black spots on the nuts are caused by a fungus. Spray the tree with Bordeaux mixture or a copper oxychloride spray when the buds begin to burst, and repeat every two weeks, especially during wet weather.
ONE OF my ferns seems slowly to be dying off. In the last few months the fronds have withered and turned brown at the tips. New fronds have grown with very stunted pinnae. At one stage the soil was covered with an oily mildew, but this seems to have disappeared since I reduced the watering. The plant was in a gloomy lounge, but I have now put it on the veranda where it gets more light, but no direct sunlight. I have recently topped up the pot with some old rotten manure.
The plant may have what is known as “brown leaf”. Cut off infected leaves and spray the plant with a copper spray. If it does not improve, I suggest you repot it in spring, as the soil may not be suitable. I base this suggestion on your statement that the soil was covered with an oily mildew. Put a few pieces of charcoal in the potting soil if you repot to help to keep the soil “sweet”.
I HAVE an apple tree that ripens September/October. For years it has been, and still is, a most prolific bearer, but for the last two years (apart from codling moth, for that I spray) the fruit just turns to a brown pulp. The tree is about 20 years old. With what can I spray geraniums? The leaves have rust and the stems seem to die back from some insect borer.
The trouble is caused by a fungus. Spray the tree twice in winter with winter strength lime sulphur (one cup of lime sulphur to eight cups of water) allowing 10 days between the applications. Cover the trunk, branches and ground under the tree thoroughly. After the fruit has formed, spray once a fortnight with a copper spray. During the summer, collect all fallen fruit and destroy it: do not put it on the compost heap. For rust, spray the geraniums with Dithane once a week, paying particular attention to the undersides of the leaves. Do not overwater the plants. For the borer, spray about once or twice a week with Sevin doing this in the late afternoon.
WHAT IS the mixture you use with cornmeal to destroy snails?
Use Garden Safe Brand Slug & Snail Bait one sprinkle in the area. After eating the bait, the slugs and snails cease feeding, become less mobile and begin to die within three to six days. One sprinkle of the bait in the area among the plants late in the afternoon, either after the beds have been watered or it has rained. Another remedy is to put saucers of beer among the plants. This attracts the snails and they drown in the liquid.
THE FRUIT on my guava tree rots at the flower end, even though we spray regularly with Lebaycid.
Your guavas have blossom-end rot, that usually occurs during abnormally wet seasons in the winter rainfall areas. Spray with Dithane or a copper spray, every 30 days from the time the fruit begins to swell and just before it ripens.
SOOTY MOULD The black, soot-like mould is not a fungus attacking the plant but one that simply lives on the honeydew excreted by insects, eg, aphids and scale. Kill the insects and the sooty mould will dis- appear.
BLACK SPOT ON ROSES
It generally occurs in the form of large, 10mm, dark-coloured spots, but sometimes appears as dark coloured blotches that practically cover the leaf. It starts to get serious in midsummer and causes a yellowing and premature leaf drop. Spray with copper oxychloride eg, Blitox, or Funginex or Benlate. that also control mildew.
Each year my amaryllis are a disappointment. I bought three bulbs about five years ago and the first year they had good blooms. The second year there were patches of a beetroot color along the stems that seemed to wither at the affected places. When the plants died down, I took the bulbs up and found the discoloration in them too, so I cut a lot away, dusted with sulphur and replanted the bulbs in fresh soil. But each year there is still some of this blight on the stems, that are stunted, and the blooms are poor, now doubled and the leaves grow well. This past season, I fed and put sulphur around them. I stopped watering at the end of summer and the leaves are almost all off. Must I renew the soil?
This is a serious disease that can cause a great deal of damage. Spray the plants every 10 days with a copper spray such as Bonide, or use a spreader such as Spreader Sticker spray to make it stick to the leaves. Soak the infected bulbs in one of these copper solutions before planting. When next you make up a soil mixture for your bulbs, add some superphosphate, about a level dessert spoonful to a large pot of soil. From the time the buds appear, feed the plants once a fortnight with a soluble concentrated fertilizer and continue feeding until the foliage dies down in autumn. This will build up the bulbs for the following season. Grow the bulbs where they get afternoon shade.