Since there are many factors involved in fruit production, there are also many reasons why fruit trees don’t produce. Here are a few of the more common ones.
· Rain- Too much rain during the bloom period can wash pollen away, and a forceful rain along with wind can actually knock blossoms off. Also, bees tend to fly less, or not at all, during heavy rains.
· High heat and low humidity during bloom will hamper pollination.
· Juvenility - Sometimes it takes many years before a tree will produce fruit; mangosteen is a good example. However, new evidence indicates the size of the tree is more of a factor than age. In general, trees grown from seed take longer to produce fruit than those that are grafted, budded, or air layered.
· Pollinators – Some fruit trees require more than one tree or one variety in order to set more abundant fruit. Examples are rambutan, macadamia, and avocados.
· Some trees require insects to help in pollination, such as durian.
· Lychee and longan need a combination of low temperatures, 50 -59 degrees Fahrenheit, and a dry period (4-6 weeks) before bloom occurs. Bloom for rambutan will be enhanced in response to drought.
· The deciduous fruit trees, like peach, plum, nectarine, apple, etc., require cooler temperatures for good fruit production. This chilling requirement is the number of hours the tree needs to experience below 45 degrees F. This requirement differs among species and varieties, ranging from a few hundred hours to over a thousand.