Primary Studies On Key Factors Influencing The Epidemic Of Potato Late Blight And Disease Control In Greenhouse

Potato late^blight is becoming one of the most serious factors that prevents the production of potato in greenhouse. In this study the epidemic of this disease was assessed based on the analysis of the meteorological date either in or out the greenhouse which collected daily through the whole growing season. Plant extracts were tested for the inhibition to the germination of the sporangia and to the mycelium growth of Phytophthora infestans. The plant extract was also tested on the detached leaves of potato and on seedlings in greenhous.The result showed that the disease progress curve developed in a jumping way. When the meteorological condition were met, P. infestans would produce lots of sporangia and infect the potato severely within one day. Lower temperature and higher relative humidity benefit the disease. Precipitation is essential to the developing of the potato late blight.The crucial weather condition for highly sporulation and severe infection of P. infestans is defined as a period of 24 hours with ?the air temperature ranging from 10癈 to 25"C ;