Disease Management
It may seem like the worst is over, but apple growers should continue to be vigilant and apply fungicides even as we approach the end of the ascospore discharge period. Leaves are still highly susceptible to both primary and secondary apple scab infection until the terminal bud has set and the leaves have hardened off.[Read More…]
Grapes in the southern half of the state will soon be reaching the critical pre-bloom stage, which is a key time to control important diseases such as black rot, downy mildew, and powdery mildew. The three or four sprays made from immediate pre-bloom to 4 weeks post bloom are critical for controlling fruit infections. Growers[Read More…]
Diagnosing Phytophthora crown rot is difficult. First examine the crown and rule out any type of mechanical damage, including rodent damage. Early symptoms of root and crown rot include delayed bud break, small leaves (often with leaf discoloration), and twig dieback. Bark discoloration, unthrifty growth, and premature leaf drop may occur later in the season[Read More…]
Wet weather continues to be a problem, not just for foliar disease, but root and crown rot, as well. Phytophthora root and crown rot is observed in wet spots: low-lying areas of orchards with heavy, poorly-drained soils. These pathogens can infect all fruit producing plants. Occurrence of this disease is sporadic and tied to wet[Read More…]
Although not always possible, avoid planting in low-lying, flood prone areas. Control weeds around the trunk of apple trees, as many serve as alternate hosts for the crown rot fungus(especially nightshades). Reduce nitrogen application on young trees, and trees with excessive growth as they are more susceptible to crown rot. As there are different species[Read More…]
The weather the past 3 weeks has been ideal for development of Phomopsis cane and leaf spot. Temperatures have been cool with frequent rain, and shoot growth has been slow. These conditions favor sporulation and infection by Phomopsis viticola. This pathogen is one of the major causes of fruit rot in the Midwest. Early season[Read More…]
The recent spate of cool, wet weather has left one organism happy, Venturia inaequalis, the fungus that causes apple scab. Most of the state just underwent an extreme scab period, and unfortunately, few of us could do anything about it because of the combination of rain and wind. The revised Mill’s table (from http://www.fruit.cornell.edu/tfabp/revmills.htm )identifies[Read More…]
Upticks in powdery mildew last year, plus a mild winter (which allows the fungus to overwinter in buds) set the stage for powdery mildew (Fig.3). Early season rains kept things at bay, but the recent change to drier weather while leaves continue to grow sets the stage for this disease. Powdery mildew is active during[Read More…]
Grape growth is a bit ahead of normal this year. Grapes are at the critical early shoot growth stage when Phomopsis cane and leaf spot infections occur. This is a critical time to take preventative control measures for this disease. If left unchecked, the early shoot infections will spread to cluster stems and developing berries.[Read More…]