The annual growth and decline of aerial spores can be divided into four different stages, namely, the winter foreseeing period, the popular initial period, the popular rapid increase period and the summer and autumn regression period. The number of spores in the winter foresight period has little relationship with the epidemiology of powdery mildew. The experiment of spore trapping instrument found that the rapid increase of the number of spores in the rapid growth period is the manifestation of disease epidemics. Only the epidemic period is the key moment to determine the epidemic intensity of powdery mildew. .
The optimum temperature for spore trapping is 20-25 °C, and the daily average temperature is lower than 19 °C or higher than 26 °C. Rainfall can promote the sedimentation of spores. Therefore, the catch in rainy days is small, and the amount of catching after the rain increases sharply. The breeze is conducive to the spread of powdery mildew, and the spore trapping device increases the amount of spores, but the wind speed is less than 0.2m/s and the sporulation is higher than 3.0m/s.
The number of aerial spores is closely related to the condition of powdery mildew in the forest. Tests on the capture value of spore traps showed that the number of aerial spores was positively correlated with the total incidence of forest sections after 5-7 days. When the number of spores per slide reached about 10, the number of spores increased sharply, and the disease increased in the forest after 5-7 days.
Mastering the occurrence and quantity dynamics of aerial spores during this period by spore trapping instrument is the condition and basis for predicting the final condition and determining the first application period. Spores appeared in the airborne powdery mildew spores in the early winter and early spring when the gum tree began to pick up leaves, and the leaflet extraction rate increased synchronously with the gum tree. Subsequently, due to the increase in temperature, the young leaves are aging, the sporulation ability is reduced, and the aerial spores are gradually reduced, so that the amount obtained by the disappearing spore trap is also affected.
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