Author Archives: Luke Milliron

Howard Nut Drop

During about the second or third week in June, many Howard walnut trees experienced nut drop of perhaps as many as 100 nuts per tree, with many trees losing no more than 60 nuts per tree. These nuts were full size with the shell beginning to harden. Cutting open an immediately dropped nut, you could see darkening of the inside watery kernel material. Several possible causes are explored in this article. Continue reading

Walnut Autumn Freeze Event and Spring Regrowth Update

A sudden autumn freeze event last November is the likely cause of widespread dieback observed in both young and mature orchards in the Sacramento and northern San Joaquin Valleys this spring. Following reports in April of walnut orchards not leafing out, our initial diagnosis was freeze damage. We advisors, specialists, and faculty agree that this initial diagnosis has been further supported after examining additional orchards and weather station sites. Continue reading

Walnut Orchards Not Leafing Out

From the northern San Joaquin Valley to the northern Sacramento Valley, walnut growers are reporting a widespread and alarming issue of walnut trees not leafing out this spring. The initial hypothesis from researchers is that we are seeing frost damage from mid-November, however the symptoms on mature blocks are both more unusual and more severe than autumn freeze events in recent memory. Continue reading