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Poor pollenation, with these early drops being 'aborted' nuts. Insect pests - walnut husk maggot, in particular. Fungal disease - especially walnut anthracnose.

Nuts appear to be fine, the husk is green and no sign of husk fly or blight they just drop in early August.

Drought stress during nut maturation and poor/inadequate pollenation(cold, wet temps during bloom, or just not enough other BWs around to affect good cross-pollenation) are probably the two most common causes of nut abortion that I encounter. Feb 02, Early pecan scab infection of young nuts will cause nuts to drop and is a major cause of pecan crop failure. Black walnut is highly vulnerable to anthracnose, and the. Sep 15, Brown or black spots with yellowing are signs of anthracnose.

The underside needs to be coated but at this point it is a redo anyway.

This time of year, many black walnut trees’ leaves may have black spots, turn yellow and begin to drop. This is commonly known as anthracnose, a fungal disease that causes trees to drop their leaves prematurely.

Anthracnose is worsened by wet weather, and some trees are more genetically susceptible to anthracnose than Estimated Reading Time: 2 mins. Aug 30, In addition to premature nut fall, Walnut Blight presents first with reddish brown stem spots and young infected leaves turning dark brown or black and then dying. The Anthracnose fungus, ophiognomonia leptostyla, also causes premature nut drop with similar stem and leaf symptoms as the blight.

Codling moths are rarely an Oregon walnut problem, but an early infestation arrests nut development and may result in heavy nut drop.