Q. We have a grafted avocado planted in 1988. It sets small fruit that all drop off. We water and feed regularly, apply dormant oil spray and insecticide before blooming. How can we get fruit to set? 

A. Stop using the dormant oil and insecticidal sprays unless there is a specific pest problem. Never spray anything when the plant is in flower. Water the tree no more than twice a week or the fertilizer will be leached through the soil before the tree can use it. Some fruit drop is normal. Increase the fertilizer so the tree has the energy to carry the fruit to maturity. 

Q. My avocado has brown leaves that drop off. I have sprayed with all kinds of combinations of Sevin and malathion. What can I do? 

A. Sevin and malathion are deadly to bees, which are the pollinating insects. No bees mean no fruit. Thrips and spider mites have attacked your avocado. These sucking insects can cause leaf drop but usually do not affect the crop. Mites attack during hot dry weather. They can cause leaf drop and a rusty appearance to the avocado fruit. The fruit is still good. Try Safer's Insecticidal Soap spray for control. Use only organic products on edibles. Systemic insecticides poison the entire plant including the fruit. Safer Inc. offers a brochure that opens into a handy chart suitable for hanging. It covers many organic controls for weeds and insects that are safe and non-toxic. This should be very valuable for all gardeners concerned with the environment. It is available free; send a SASE to Safer Gardens. (See supplier's list for address) 

Q. My avocado was planted from seed in 1994 and it blossomed this year. It didn't set any fruit. Does it need another tree for pollination, or is it too young? 

A. Avocados take eight to ten years before they bear fruit, and fruit from seed-grown trees may not taste exactly like the parent plant because of cross-pollination. Avocados can be morning or afternoon bloomers, and usually need another avocado nearby for cross-pollination in order to set reliable fruit. Other factors like weather can affect fruit production. Bees do not pollinate in windy or rainy weather, so crops are highly variable from year to year. They are somewhat brittle trees, so it is best to grow them well away from the house. 

Q. My avocado tree has developed some strange looking flattened stems. I am concerned about the tree and want to know what I should do about it. 

A. Your avocado has developed fasciation, which is an abnormal proliferation of cells causing the stems to become flattened. I have a cassia tree in my yard that does the same thing. Faciated branches will often flower and fruit more, so they should be left on the tree. They may look strange, but the tree is not damaged by the unusual growth pattern. Celosia and a willow known as the fantail willow develop a similar condition. The fantail willow's flattened branches are in great demand by flower arrangers. 

Q. My 25- year old `Coquette' avocado has loads of fruit but they are small and hard as a rock and have not ripened. What do you advise? 

A. I would advise thinning out the crop which will be less of a strain on the tree and should result in larger fruit. Trees that overbear are weakened and need extra fertilizer to recover. The energy of the tree has been sapped producing so many small fruit. Cooler weather may help with the ripening. 

Q. Is the sapodilla a hearty tree? 

A. The sapodilla is a good tropical fruit tree that holds up against strong wind. The fruit was used for chicle in chewing gum and can be eaten fresh. It is brown and soft when ripe. 

Q. Our mango has delicious fruit. Should we harvest it while it is green or wait until it ripens on the tree? 

A. Allow some fruit to ripen on the tree and pick some while green. Extension Service offices have recipes for both green and ripe mangoes. You can ripen the green fruit in a paper bag with an apple in it. The apple gives off ethylene gas, which will help to ripen the fruit. 

Q. My young mango dropped all its fruit when it was half grown. What can I do to prevent this? 

A. Grafted mangos need to be four to five years old before they set fruit. Seedling trees may take eight to ten years. The trees may not have been old enough or had enough nutrition to carry the fruit to term. The older the tree, normally the better the crop. Use citrus/avocado fertilizer in March, June and October to encourage fruit yields. 

Q. Our 46-year-old Hayden mango has been diagnosed with anthracnose. It needs to be sprayed with copper fungicide. When should it be sprayed? Who should I get to spray, and how much will it cost? 

A. Anthracnose is a fungus that causes twig cankering and dieback, spotted dropping leaves and spotted fruit with bad areas. Anthracnose is difficult to completely control. Many people simply live with it, but it does affect fruit quality and the mango foliage always has brown edges. Certain mangos are quite resistant; the Philippine types such as Saigon, Cecil, and Cambodia are not very susceptible to anthracnose and produce good quality fruit. To control anthracnose use copper fungicide, Zineb or Maneb, weekly from just before the flowers open to fruit set. Afterward spray monthly till mid-May for early varieties and mid-June for late varieties. The copper can stain objects blue, so caution should be used when applying. The larger the tree, the higher the cost. Call at least three pest-control companies for estimates. They may have to see your job before giving you a price. Most mangos grow 50 to 60 feet, and most hose sprayers will reach only to about 20 feet. If you want a dwarf variety that grows to only 20 feet, try `Julie'

. Q. I had an edible fig tree in Long Island that grew well and produced fruit. We have some potted small trees and I would like to try one here. Will the fig grow here, and what care does it need? 

A. Edible figs are a bit south of their best growing conditions in South Florida. `Brown Turkey' is one of the best varieties for this climate and grows to about 15 feet. Plant in an open location in full sun with good air movement and drainage. To minimize nematode damage keep the tree permanently mulched to a depth of at least 2 inches. Keep the mulch at least 1 inch away from the stems. Water in the morning only between 2 and 10 a.m. Keep water off the leaves if possible. Figs like good air movement to minimize the rust disease, which causes the leaves to fall off. When you see reddish spots on the leaves, spray with copper fungicide, following label directions. Repeat treatment in 10 days. Fertilize with citrus fertilizer in March, June and October. 

Q. How can I get my figs to ripen once they are off the tree? 

A. Put the figs in a bag with an apple after you pick them from the tree. This should ripen them up in a few days time as the ethylene gas from the apple stimulates ripening. 

Q. I planted a carambola seed that I got at Mounts Botanical Garden. I put it near the house. It has grown to 7 feet tall. How should I care for it? 

A. I certainly would move it out from the house wall into an open area where it will have room to develop properly. Most tropical fruit trees will grow to 30 feet tall and need lots of space and light. Look for fruit after about eight years. Feed with citrus fertilizer in March, June and October. 

Q. My papaya has bugs in it. What can I do to stop them from getting into the fruit? 

A. Papaya fruit fly is a major pest in this area. Spraying is not effective. Some success has been reported bagging the fruit with heavy brown bags. The small fruit fly cannot penetrate the bag and fruit to lay its eggs, which hatch out into worms. Do not use plastic bags. The fruit will rot and turn to mush under a plastic bag. You have to love papaya to go to all that trouble. Research is trying to develop a thick-skinned papaya that the fruit fly cannot penetrate, so there may be hope in the future. 

Q I have a mastwood tree. I don't know much about the tree or it's fruit. If squirrels eat the fruit it does that mean I can eat it too?

A. Your trees are calophyllum, commonly called beautyleaf or mastwood. Calophyllum is strong wooded and fairly salt tolerant. The fruit shouldn't harm the squirrels, but should not be eaten by humans. Calophyllum is very sensitive to cold, so it may suffer some dieback in cold winters. 

Q. My young `Mauritius' lychee tree is 12 feet tall and has brown-tipped leaves. I feed it 6-6-6, Epsom salts and Milorganite in March, June and October. I am not sure how much to use. What causes the brown tips and is my fertilizer mix OK? 

A. It would be better to use a regular citrus fertilizer, which would be higher in minor elements and more appropriate for the tree. Follow label directions on the fertilizer bag for application rates. I usually sprinkle the fertilizer lightly and evenly like salt on a hamburger, starting 1 foot from the trunk and fertilizing out to about 2 feet beyond the outermost branch spread. You can then water the fertilizer into the soil for 10 minutes or apply before a rainstorm. The Milorganite is mostly nitrogen and the Epsom salts is magnesium, which is one of the minor elements. The times you fertilize are fine. The `Mauritius' variety fruits on a more regular basis than the `Brewster' variety, which often fruits only every three or four years. The lychee leafs out early in the year and foliage is subject to windburn or cold damage as it emerges. The tree gets hardier as it grows older, but needs protection from the wind. The brown tips seem like standard equipment but the more balanced citrus fertilizer should help. Lychee seems to like damp conditions with an even supply of water through the year. Mulch the tree to help water retention, but keep mulch 1-2 inches away from the trunk. Water the tree about twice a week if there is no rain. Lychees seem to like the inland muck soils better than the sandy soils along the coast. 

Q. You mentioned a chutney tree on your radio show and I want to get one but I don't know what to ask for? 

A. You are looking for the Indian tamarind, which lasts in strong hurricane winds. It produces edible pods used in chutney and is a good, long-loved shade tree. 

Q. Are bananas easy to grow in South Florida? 

A. Yes. They like full sun, a somewhat moist location, and abundant fertilizer. Bananas also like a good permanent mulch around the base of the clump. Recycling old banana leaves and using them for the mulch is a good idea as the leaves are high in phosphorous. Use a citrus fertilizer on bananas in March, June, and October. Water plants when it is dry. Bananas can form within 20-24 months after emergence of shoots from the ground. This happens only if they are well fed. Cut the old stems down after fruiting. New shoots continue the production cycle. 

Q. Something is eating my bananas. They have holes in them. What should I do? 

A. Bananas are not normally troubled by many insects. If fruit is left on the tree too long, various scavenger beetles will feed on it. These are normally considered good guys, like nature's garbage men. Try to pick your fruit as soon as it becomes ripe. 

Q. Can I grow a cherry tree in South Florida? 

A. Cherry trees do not grow this far south. North Georgia is about as far south as they go. You might try Barbados cherry, which has a cherry-like appearance and a nice tart flavor 

Q. I have a jaboticaba that is going on six years old. I've not gotten any fruit. What should I do? 

A. Jaboticabas are very slow growing and also slow to fruit. I've seen plants in containers fruiting at 6 feet. When they finally get started, they can fruit four or five times a year. Keep the tree mulched. It bears well in sun to partial shade. I normally recommend a citrus/acid type fertilizer like a 4-6-8 to encourage fruiting in March, June and October. You might supplement this with a half strength liquid application of a bloom special to try initiating flowers and fruit. Jaboticaba probably belongs in a class in with some other ornery blooming plants. Wisteria vines in the north are famous for being erratic bloomers. My Tabebuia avellande is in the same class at the moment. It is growing madly, but puts out only a few blossoms. In Europe fruit growers sometimes partially girdle branches to stimulate fruiting, but I think this is a bit radical. 

Q. Can you eat the fruit from a loquat tree

A. Loquats are edible and considered quite good. The Cooperative Extension Office should have a loquat brochure available. Loquats get fireblight once in a while. The branch tips will die back. The best thing to do is prune out the dead wood. Loquat is otherwise pretty pest free. 

Q. I purchased a breadfruit tree in the Keys. How do I care for it in (Palm Beach)? 

A. Breadfruit is a very tender tropical tree that can be grown in Key West and the Lower Keys. It cannot endure any freezing temperatures, so will not survive on the Florida mainland. 

Q. What can you tell me about Jambolayan plum

A. Jambolayan plum is a large growing tree with very strong wood. It produces fruit heavily, probably more than the average homeowner can use. The Cooperative Extension Office has brochures on fruit tree care and recipes for exotic fruits. The Rare Fruit and Vegetable Council is a good organization that provides interesting lectures on tropical fruits and features taste tables where you can experience some fine tropical delicacies. 

Q. How do you handle a macadamia tree

A. Macadamia trees can be handled like citrus. They are more tolerant of water than citrus so are not subject to root rot. Fertilize in March, June and October with a citrus/avocado fertilizer. Spread the fertilizer evenly over the ground from about 1-foot from the base of the tree to the outermost branch spread known as the drip line. Macadamia trees set a good crop if there is another macadamia nearby for cross-pollination. The trees often set more fruit than