Blossom and fruit drop and fruit splitting are fairly common problems for fruit trees. While losing blossoms and small fruit from your fruit trees can be disturbing, it is most likely a natural process.
Trees that bloom profusely, like the mango and avocado, could not possibly hold all of the fruit that forms on each limb. So it sheds the excess.
You can also remove some small fruits yourself, which will increase the size of those allowed to mature.
Or other stresses could be affecting the tree. A proper fertilizer program should be maintained throughout the year. With little or no fertilizer, the tree will not have the essential nutrients for growth and fruit production. A balanced fertilizer containing the proper micro-nutrients and the basic macro-nutrients should be applied several times a year.
When nutrition is responsible for blossom and fruit drop, nitrogen deficiency is frequently the problem, although phosphorus and zinc deficiencies are common.
The best way to treat a nutritional deficiency is to prevent it by using a fertilizer containing all the elements necessary for proper growth. Look for a fertilizer labeled as a fruit special. This blend will have the micro nutrients necessary for fruit production.
Improper watering is one of the primary causes of blossom and fruit drop. The roots of a citrus tree spread outward just below the soil surface. The bloom period occurs during the dry season, so it is easy for your tree not to receive an adequate supply of moisture. Observing the weather conditions and watering at regular intervals during the dry periods will help prevent fruit loss.
Poor pollination can also cause problems. Often two types or cultivars of a particular fruit tree are necessary for proper pollination. You can check the subtropical fruit literature at the public library or County Extension Office to determine whether your tree requires a pollinator or not.
Finally, strong winds will cause blossoms and small fruit to drop. Even mature fruit will fall if the winds are strong enough, as those who cleaned up after Hurricanes Andrew and Wilma can attest.
Fruit splitting usually occurs in September and October. This can happen when not enough copper is available to the tree. Splitting also can be a problem when there is an acute deficiency of other elements necessary to plant growth.
During certain times of the year, there may be periods of heavy rainfall or drought. The problem is often accentuated just after a period of moisture stress, followed by heavy rains.
The tree takes up considerable moisture and forces it into the fruit. As the fruit nears maturity, the rind becomes less pliable and fails to expand properly. Some varieties and young trees are more susceptible to this problem than older, bearing trees.
There is nothing you can do for the current crop. Next year, splitting can be lessened by a balanced fertilizer program containing the necessary minor elements and by more uniform irrigation during the fruiting season.
You should remove the affected fruit as it can attract insects.
Plant of the Week
Desert rose — adenium obesum
• Member of the cacti family
• Shrub to 5-feet high with moderate growth
• Pink flowers all year
• High salt tolerance
• Full sun but will tolerate partial shade
• This is a great plant for pots but will obtain maximum height if planted in the ground.
Eileen Ward and her husband, Peter, own and operate Greensward of Marco Inc., a lawn maintenance and landscaping company. Besides completing horticultural courses from the University of Florida, she has a commercial maintenance spray license and is a registered dealer in agricultural products in Florida. To reach Ward, call 394-1413.