Premature loss of nuts For many years, lack of pollination causes the greatest loss of nuts. Since pecans are pollinated only by the wind, excessive rainfall during spring bloom prevents pollination, as noted above, and poorly pollinated flowers produce small nuts that later abort. Alternate nut production (intermittent years) is mainly the result of inadequate fertilization. When trees produce a large crop of nuts, there are not enough nutrients for that year's nuts to ripen and for the tree to store enough plant food for adequate production the following year.
Early defoliation in fall usually means that there will be no harvest of nuts the following year. Diseases and insects that affect leaves also contribute to the alternation of production by causing early leaf fall in autumn. Alternative production is believed to be an adaptive response to reduce pest pressure by not allowing a constant supply of nuts, so pests can thrive. While pecan trees can produce a crop each year once they start, abundant nut crops are produced every other year.
The phenomenon, called alternate bearing, means that trees produce light yields in other years. Years of neglect can aggravate and accelerate the aging process of walnut trees. Reintroducing proper maintenance can bring a tree back into production. Since pecan trees need a lot of water, you may need to modify your watering schedule.
In many years, the lack of pollination causes the greatest loss of nuts. Since walnuts are only pollinated by the wind, excessive rainfall during flowering prevents pollination and unpollinated nuts fall off. The weather conditions of some seasons cause male and female flowers to ripen at different periods and pollination does not occur. I have a nut tree that hasn't produced nuts for the past 4 years.
It is impossible to spray the tree. The most important disease in walnut trees is nut scab, especially on older trees that cannot naturally resist disease mutations.