Downy Mildew in Organic Leafy Greens
Organic Leafy Greens
Fresh leafy greens consumption has increased dramatically over the last 20 years in the US. Most of the acreage of US fresh market production occurs in California and Arizona. Unfortunately, with the increase in acreage has come an increase in risk from disease. The most important disease for fresh market leafy greens production in the Western US are downy mildews.
Spinach Downy Mildew
Spinach downy mildew, caused by Peronospora effusa, is the most serious threat to fresh market spinach production in California and Arizona. New pathogenic race types have overcome a series of resistant lines and threaten the long-term stability of the industry. A quantitative PCR (qPCR) method was used in conjunction with spore traps to monitor the amount of P. effusa present in the Salinas Valley. Four sites throughout the valley were monitored in 2013. In addition to spore trapping, weekly disease incidence ratings were performed using cluster sampling near the trap sites.
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Lettuce Downy Mildew
Lettuce downy mildew, caused by Bremia lactucae, is a serious and persistent threat to lettuce production in the Western US. The disease can reduce both the quality and yield of the lettuce. Although there is resistance to the disease, downy mildew can affect all types of lettuce, including head, leaf, and romaine. We will use our spore traps to monitor and help predict disease outbreaks.