Hosts and symptoms
''Peronospora trifoliorum'' commonly infects numerous strains and varieties ofEnvironment
''Peronospora trifoliorum'' prefers high humidity and moderate to warm temperatures. Peak spore production and infection occurs around 65°F, though the pathogen is active in temperatures between 40 and 85°F (Goldberg, 2000). This means that ''Peronospora trifoliorum'' is primarily seen during cool, wet periods in the summer or warmer, dry periods in the spring and fall, and is usually found in the midwestern and southern United StatesUW-Extension. (2006). Alfalfa Diseases. Retrieved fromManagement
Growing resistant varieties of alfalfa is the most common form of control used against ''Peronospora trifoliorum'' (Samac, Rhodes, and Lamp, 2015). A form of cultural control, resistant varieties limit the ability of the disease to infect and survive in the plant. Another cultural control is to cut the alfalfa crop early, which removes the infectious conidia (Samac, Rhodes, and Lamp, 2015) while limiting the amount of foliage lost, removing the infected tissue, and decreasing the moisture and humidity through increased air circulation (Pacific Northwest Extension, 2019). While cultural controls are believed to be the most effective form of control against ''Peronospora trifoliorum'', the use of chemical control in the form of metalaxyl and mefenoxam is common and effective for alfalfa seedlings (Samac, Rhodes, and Lamp, 2015). These systemic fungicides are used to suppress the infectious stage of the disease. Additionally, there have been attempts to find alternative methods to control ''Peronospora trifoliorum'': a 2011 study used various biotic and abiotic compounds to test the use of bio- and chemical controls on different alfalfa diseases. The study found that to some degree, salicylic acid, potassium phosphite, neem oil, Bio-Arec, and Bio-Zaid betaine all protect against downy mildew and numerous other alfalfa diseasesMohamed Morsy, K., Fawzy Abdel-Monaim, M., & Mamoud Mazen, M. (2011). Use of Abiotic and Biotic Inducers for Controlling Fungal Diseases and Improving Growth of Alfalfa. ''World Journal of Agricultural Sciences'', (7), 566–576. Retrieved fromReferences
External links
{{Taxonbar, from=Q7169463 Peronosporales Species described in 1863 Water mould plant pathogens and diseases Pulse crop diseases Medicago Plant pathogens and diseases