Matters needing attention in soilless cultivation of flowers, common diseases and insect pests-black spot

Symptomatic leaves, petioles, twigs and pedicels could be damaged, but mainly damaged leaves.

There are two types of symptoms: one is the appearance of reddish brown to purplish brown spots in the early stage of the disease, which gradually expands into a round or amorphous dark black spot, which is often surrounded by a yellow halo, the edge is radial, and the diameter of the spot is about 3ml 15mm. In the later stage, there are small black spots on the plaque, that is, the conidial disk of the pathogen. In severe cases, the lower leaves of the plant are withered and yellow, and the leaves fall in the early stage, resulting in the death of individual branches, such as black spot of rose.

The other is the emergence of brown to dark brown nearly round or irregular wheel spots on the leaves, on which black mildew grows, that is, the conidia of the pathogen. In severe cases, the leaves fall early, affecting growth, such as black spot of elm leaf plum.

Black spot is the main disease in rose, which occurs widely and causes serious damage. The pathogen overwinters in withered branches or soil in the form of mycelium or conidia. The infection began in the middle and late May of the following year, and the peak period was from July to September. Conidia spread, spread and re-infect by wind, rain or insects.

Rain Water is the main condition for the prevalence of the disease. the disease occurs early and seriously in years with early and more rainfall. Low-lying stagnant water, poor ventilation, lack of light, improper fertilizer and water are conducive to the disease.

Prevention and cure method

High quality and disease resistant varieties were selected for ①.

② eliminates withered branches, fallen leaves, and destruction after autumn.

③ should strengthen cultivation management, pay attention to shaping and pruning, ventilation and light transmission.

When ④ new leaves are unfolded, spray 50% carbendazim wettable powder 500m 1000 times, or 75% chlorothalonil 500x, or 80% Dysen zinc 500x, 7 Mel once every 10 days, 3 Mel 4 times in a row.