Disease Archives - Page 2 of 3 - West Coast Nut

-Advertisement-

Disease



The Latest on Disease Resistant Rootstocks


Significant progress is being made in the development of walnut rootstocks that possess resistance to the major yield limiting diseases and soil-borne pathogens. “We are now working on putative disease resistant walnut genotypes which are being propagating to test in large scale field trials to determine how they perform compared to the greenhouse evaluations, “ said Dan Kluepfel, United States Department of Agriculture (USDA)/Agricultural Research Service (ARS) research scientist and principal investigator of the walnut rootstock development program. “This is not just an academic pursuit. We have something in hand and in collaboration with nurseries are moving forward to place these rootstocks in field trials.” Disease-resistant Rootstocks Disease-resistant rootstocks for commercial walnuts are a huge deal for growers, said Cliff Beumel, a long time walnut grower and nurseryman and President of the fruit, nut and olive tree nursery Agromillora located north of Sacramento near Gridley. “All growers eventually bump up...

Read More

Managing Hull Rot in Almonds


Prevention of a fungal disease that can affect almond yields for many growing seasons starts with a correct diagnosis and understanding of disease biology. Hull Rot Almond hulls are susceptible to hull rot fungi from the beginning of hull split until the hulls are dry. This period can last from 10 days to two months depending on the irrigation and fertilization management of the orchard. There are no control measures once hull rot infections are visible. University of California (UC) Riverside plant pathologist Jim Adaskaveg identified the ‘deep V’ stage of hull split as the stage when almonds are most vulnerable to hull rot infections. Dr. Mohammad Yaghmour, University of California Cooperative Extension (UCCE) farm advisor for almonds in Kern County is conducting research to determine control measures for hull rot. He was one of the seminar speakers at Almond Day in June and outlined best management practices and treatment...

Read More

How to Handle Aflatoxin Rejections: Why They Occur, How to Avoid Them


How to Handle Aflatoxin Rejections: Why They Occur, How to Avoid Them Having a shipment of almonds rejected by an overseas port for excessive aflatoxin can be expensive, and it’s especially frustrating when pre-export testing appeared to show that the lot in question was fine. (more…)

Read More

Managing and Controlling Canker Diseases in Almonds and Walnuts

By Cecilia Parsons Associate Editor

Options to control Botryospaeria (BOT) diseases in tree nut crops include good sanitation and cultural practices to reduce the amount of inoculum in the orchard. University of California plant pathologist Themis Michallides covered the range of BOT diseases that affect walnut, pistachio and almond trees and how growers can reduce infection at the South Valley Nut Conference in Tulare.   Panicle and Shoot Blight of Pistachio Panicle and Shoot Blight of pistachio was discovered in 1984 in a commercial orchard in northern California and has become a disease of major importance. Buds infected by B. dothidea either will not emerge or will emerge, but the flower or shoot eventually dies. Symptoms of the infection are dark lesions at the base of shoots, rachises and mid ribs of leaves. Later in the growing season, brown, blighted shoots and leaves are easily seen among healthy foliage. Buds are highly susceptible to infection...

Read More

Distribution of Chlorosis in Almond Orchards

Distribution of Chlorosis in Almond Orchards

By: Elizabeth J. Fichtner, Farm Advisor, UCCE Tulare and Kings Counties;
and Mae Culumber, Farm Advisor, UCCE Fresno County,
and Bruce Lampinen, Extension Specialist, UC Davis

The first step in assessing the cause of canopy chlorosis and decline in an orchard is mapping the distribution of the symptoms. If a pattern of chlorosis is similar across irrigation lines, then the cause of the problem may be related to over—or under—watering. Two scenarios present themselves regularly during summer farm calls: a) terminal tree chlorosis, and b) within row tree chlorosis (Figures 1 and 2). Figure 1. A) Chlorosis of end tree indicates excessive water on last tree in row; B) Chlorosis of overall orchard with healthy tree at end of row indicates overwatering at orchard level, and appropriate water to end tree. (Photos: B. Lampinen   Terminal Tree Chlorosis   In some orchards, the terminal tree along the irrigation line may become chlorotic and decline in advance of mortality. If terminal tree chlorosis is a trend throughout the orchard, it is worth assessing the sprinkler distribution at...

Read More