My mature chestnut trees don’t produce full-term, filled-in nuts. What could be the problem?
Answer: After consulting with chestnut experts in California and Florida, as well as delving into the published research, all sources seem to point to a pollination problem. However, since chestnuts are pollinated by both insects and wind, it is unlikely that having no pollinators is the problem.Rather, cross-pollination is likely the problem. But the experts agreed that your three different species should solve this unless there is a noticeable “asynchrony” in bloom time (meaning they don’t bloom at the same time). Even then, the fact that you have three different species and several different varieties should render that idea irrelevant.There is no sense in going out and buying another tree because it would take too long for it to come into flowering. However, you mentioned that there are other chestnut trees in the area that produce nuts that fill out. During this coming spring’s bloom period, make contact with the owners of those other trees and take “bouquets” (prune some blooming twigs off), put them in a coffee can or something similar, put some water in the can, and hang these in the trees. Try to make six to 12 of these hanging bouquets and try to take them from different trees. Isolated pear trees have been made to bear fruit this way, and this technique might work for you.If it does work and you get filled shells after doing this, then you at least know the problem is cross-pollination and then it might make sense to try to bud or graft some of your neighbors’ trees onto small limbs of your trees, or buy yet another tree.