1.  Worms in fruits

2.  Avocados

3.  No fruit on Mango tree

4.  Brown, dry Mango blooms

5.  Mango leaves burned at leaf tips

6.  Black spots on Mango leaves

7.  Where can I buy tropical fruit trees?

1.  Every year I get little worms in my Guavas and Papayas.  What are they and can anything be done?
These are probably the larvae of the Caribbean fruit fly. This pest is a problem on all fruits which are fleshy and which stay on the tree a long time before ripening. The fly deposits an egg just below the surface of the skin and the larvae feeds throughout the fruit as it matures. Upon maturity, a fly emerges from the fruit. The larvae are usually so numerous the fruit is inedible. Frequent and persistent appropriate sprays throughout the fruiting period will give only poor results in controlling this pest; bagging fruits with paper bags is probably more effective.

2.  I grew an Avocado from seed and planted it in my yard five years ago, but I have yet to see a bloom or fruit.  What can I do to make it bloom? 
Avocados grown from seed rarely produce fruit before 8 to 10 years, and such fruit may be of poor quality. The homeowner who wants an Avocado tree for its fruit production should either obtain a young grafted tree or propagate his own. Budded or grafted trees will produce within 2 or 3 years. (This fact holds true for citrus also).

3.  Why did my Mango tree not have any fruit on it this year and what can I do now to make sure I have a crop next year?  Mature Mango trees need to be stressed to become fruitful.  The Keys growing conditions are so favorable, we must induce stress sometimes.  First, prune immediately after harvest to remove dead branches, lower the height, etc.  Second, apply a slow release fertilizer 3-4 times a year in February, April, June, and August (5-6 lbs. per application of 6-6-6) and water if drought stress occurs.  Third, withhold any fertilizer and water from September through January until after fruit has set.

4.  Why are my Mango blooms, especially during the dry weather (March & April), suddenly turn brown and dry up?  This is usually due to a disease called powdery mildew.  Examine the bloom closely for white masses of infection.  It can also affect fruits and leaves.  The use of a fungicide treatment will treat the infection.  See: "Common Diseases of Mango in Florida" at:  http://edis.ifas.ufl.edu/VH048. 

5.  What causes Mango leaves to die or burn at the leaf tips and along the margins?  Leaf burn may be the result of salt toxicity or over-fertilization, anthracnose infection, soil contamination, excessive animal waste, spray burn, bark scale infestations, or being too close to salt water. Prevention of salt toxicity or soil contamination is the solution.  If this should occur, leaching the soil with continuous applications of fresh water will help.  This should be done all in one day.  Once leached, you should prevent contamination from occurring again.

6.  What is the cause of black spots on the leaves of Mango trees?  Anthracnose infection.  Black spots appear on both young and old leaves, bloom, and fruit.  On the leaves, the black spots go all the way through the tissue.  On young leaves, the black spots appear along the margins causing leaf curl and leaf drop.  The disease causes flowers to drop.  After the flowers have fallen, the bare bloom spikes have a darkened, dirty appearance.  Young fruit will become deformed and split, eventually dropping.

Applications of copper fungicides as new tissue develops and protecting the expanding tissue will prevent anthracnose infections.  For infections that come following nutritional deficiencies or wounds, prevention is the only successful control.  Prevention involves spraying weekly from the first appearance of the flowers until all fruit have set with copper fungicide sprays (always follow label directions).  To prevent fruit infections, sprays must be  applied from the time the fruit sets until mid-May to mid-June depending on variety.  See "Common Diseases of Mango in Florida" at: http://edis.ifas.ufl.edu/VH048. 

7.  Where can I purchase tropical fruit trees? See: http://edis.ifas.ufl.edu/pdffiles/CN/CN00800.pdf