白霉:危险因素总结

This page was adapted from the article, "白霉:危险因素总结," which appeared in 作物 & 害虫的报告 2022年7月28日.

In some areas of the state the risk for white mold has increased. 视乎作物的生长阶段而定, proactive management of white mold could be considered if your risk is high. 下面是你可以考虑的十个因素的总结.  

发展阶段:

• Broadleaf plants become susceptible to white mold only once they begin blooming (sunflowers are an exception).  This is because the pathogen needs to utilize the flowers as a food source to cause infection.
• 在一般情况下, the optimal time to manage white mold with a fungicide application will be somewhere in the early bloom stages of the crop. Applications made in later growth stages miss the critical window to prevent economically important infections.

天气和小气候:

• 土壤水分. 土壤s must have some water to begin the disease cycle (when sclerotia germinate 🡪 生产apothecia 🡪 产生子囊孢子). 从历史上看, only 1-2 inches of rain falling in a 1-2 week period before plants enter bloom is considered the 最低 needed for sclerotia to germinate, 生产apothecia, 和 release ascospores.
• 开花期间的温度.  Sclerotinia infection 和 development is optimal when daytime highs are cooler; especially the 60’s 和 70’s. White mold can occur at higher temperatures, but it requires longer periods of leaf wetness. 
• 开花期间树冠的湿度.  White mold is favored if the plants are wet for long periods of time. Rain, fog, 和 heavy dews during bloom are all favorable for disease.  
• 冠层密度和冠层闭合. These factors make a BIG difference on the environment in the field, 和, we learned recently also impact spray timing 和 droplet size (see article below).  一旦树冠闭合, the crop is likely to have a more favorable microclimate for infection 和 disease development.

作物及历史:

• 领域的历史.  Fields that have a history of white mold are often more likely to experience epidemics.  Sclerotia (the pathogens survival structure) can survive for many years in a field, so an epidemic a few years earlier may still be influencing this year’s growing season.  Consequently, just because we experienced a drought last year doesn’t mean we won’t have disease.
• 轮作.  A field with a short rotation among susceptible broadleaf crops is more likely to have white mold problems than a field with no white mold history 和/or long crop rotations.
• 作物.  所有阔叶作物都可能得白霉, but we tend to see sunflowers 和 dry edible beans be among the most sensitive 和 flax among the least.
• 遗传学. While most broadleaf crops do not have ‘resistant’ varieties, 有些品种会比其他品种更不敏感. 在大豆, 易感性的变化是非常明显的, 和 soybeans with longer maturity groups are generally more susceptible.