I’ve had a lot of calls over the past couple of weeks regarding the dropping of green, healthy-looking leaves on ‘Desirable’. Looking back in my notes, this is something that seems to happen every year but we often have short and selective memories and choose not to remember seeing it. Much of this minor leaf shed is simply the dropping of shaded leaves in the interior of the tree. A good, look at ‘Desirable’ trees often reveals a fair amount of bare limbs on the interior of the tree that the tree simply self-prunes.
Changing environmental conditions can also trigger this leaf drop. We’ve had 6 months or so of pretty saturated soil conditions. This can sometimes lead to the death of a few feeder roots. As the soils dry out and the temperatures heat up, the tree often responds by letting go of a few leaves. At any rate, this early summer green leaf drop by ‘Desirable’ is largely inconsequential and doesn’t really pose a problem. It is simply a physiological response of the tree and is not related to a nutritional problem. It occurs each year and if you do not notice the defoliation when looking at the tree from a distance, but only see it when you look under the tree, there’s no worry. Growers with ‘Desirable’ in 2014, have more to worry about in the form of scab than they have in a minor leaf drop.
We began seeing some nut drop on “Desirable’ toward the end of last week. This is the normal “June drop” and is the result of poor pollination and/or fertilization of the embryo. This is a characteristic of ‘Desirable’, which always sheds fruit down to 1 or 2 nuts per cluster, but it still maintains good yields. This is why ‘Desirable’ can produce a crop year after year.