Author Archives: David Doll

About David Doll

David Doll is a University of California Cooperative Extension nut crop pomology farm advisor for Merced County.

Alternaria leaf spot of almond

The late rains we are receiving will increase the risk of Alternaria. This pathogen (Alternaria alternata) requires warm temperatures and leaf wetness to infect almond trees. A few weeks after infection, small circular lesions form, eventually increasing to the diameter of 1/2-3/4.” Occasionally, there is a yellow halo. Older lesions often develop a black ring of […]

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Yellow Trees from Being Too Wet

It is very common to see yellow trees in the spring. The lack of color is often due to saturated soils which reduces the movement of oxygen into the soil, killing fine feeder roots. This impacts the ability for the tree to take in water and nutrients, leading to micro-nutrient deficiencies, impacting nut set and […]

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Bacterial Canker and Blast

Over the past few weeks, there have been a high frequency of problems reported with bacterial canker and blast. Bacterial blast results in blighted blossoms and causes crop loss. Interestingly, when there is a high frequency of blast, the very similar disease of bacterial canker appears a few weeks later in young trees(we are starting to […]

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