Question
QUESTION: I have a lemon or lime (the citrus are green but my landlords say it's a lemon tree) in my backyard. It has a white fungus that collects on and around the fruit, and there are tons of small black ants on the tree, as well as a lot of spider webs. What can I do to safely heal this, or is it beyond saving? My landlords say the tree has had a fungus for a while. Also, some of the limes/lemons grow in unusual shapes, but I'm not sure if that's natural or not. Thanks!

ANSWER: Sounds like you have aphids and powdery mildew. Aphids are small insects that suck the plant juices from the plant deforming the leaves and/or fruit. Powdery mildew is a fungi that coats the leaves with the white/grey covering. I would suggest you go to a nursery and but a ready to use insecticide fungicide combination spray. This will take care of the aphids and the powdery mildew. make sure you completely cover the leaves with the spray solution. Since the condition has been there for a time you may have to make a couple of applications of the spray about 10 days apart. I would try three applications. Then this next spring fertilize the tree . Fertilization should occur immediately before bloom or leaf sprout occurs which is usually in March. A good general recommendation for rate to use per tree is one pound of fertilizer per inch trunk diameter. Use 21-0-0 or ammonium sulfate if your soil pH is above 7.0. A complete fertilizer such as 15-5-10 can be used if your soil pH is below 7.0.

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QUESTION: Thank you for the response. Is there any way I can heal the tree without using a chemical insecticide or fungicide? I have other plants near the tree with edible parts and I would rather not use harmful chemicals, if I can get around it. Maybe a soap solution or a similar fix?
Thanks!

Answer
For the aphids there are couple of treatments these work less than the insecticides. For the powdery mildew there is a alternate BUT I do not know how well it will wrok.

Apgids
Biological Control - Encourage Predators and Parasites Lady beetles, green lacewings, hover flies, and parasitic wasps commonly do a good job of aphid control if they are not killed with insecticide applications or if ants are not allowed to tend the aphid colonies. If ants are tending aphids on a plant, place a ring of insecticide dust or diatomaceous earth around the base of the plant. If the plant has to be sprayed with an insecticide, use a "softer" material such as horticultural oil (1.5-2.0 percent) or an insecticidal soap. These materials tend to cause less harm to the beneficials.

Chemical Control - "Soft Pesticides" Since most aphids are soft-bodied insects, horticultural oils and insecticidal soaps seem to provide good control. Thorough coverage is needed since these products have contact activity only. Request a fact sheet on horticultural oils for information on product specifications, tolerant plant materials and rates.

Powdery Mildew
An alternative nontoxic control for mildew is baking soda (similar to the potassium bicarbonate listed above) combined with a lightweight horticultural oil (Sunspray). Researchers at Cornell University have discovered the fungicidal properties of this combination against powdery mildew on roses. Applications of 1 tablespoon baking soda plus 2.5 tablespoons of Sunspray oil in 1 gallon of water are still experimental. Use it at your own risk.