First:Occurrence and harm
Hazard: early deciduous leaves will affecting fruit yield and quality, illness caused by secondary flowering,weaken the tree vigor.
Variety: all cultivars are susceptible to disease at present.
Distribution: All apple producing areas are easy sick.
Main reasons: prevent and control technology is not good use and apply pesticide times are few.
Apple brown spot can lead to early fall leaves.
Second:symptom diagnosis:
Typical Symptoms: brown spot,yellow leaves , brown spots.
Symptom
Needle type
Concentric wheel type:
Brown type:
In the early of disease,it can forming a brown round lesion
It has brown withered spot and the center has small brown point.
Fruit lesions:brown spot bacteria infected fruit and formed brown point. After enlarged will become brown and round lesion.it have slightly concave and clear edges.
Third, the occurrence and prevalence
The occurrence of the disease and epidemic has related with rain, cultivation and management ,breed . the spread and invasion of conidia need water,so rain is the main condition of the disease epidemic.
Fourth, the prevention and treatment methods
Reasonable pruning, pay attention to drainage, improve the ventilation and light conditions.
Cleaning leaves, diseased branches, sick leaves buried or burned in autumn, winter .
Spraying pesticide: generally began spraying in mid-may , interval 15 days , total 3-4 times.
Pesticides formulation:
Triazole fungicides have a better therapeutic effect on brown spot disease, such as tebuconazole, propiconazole, fluorosilazoles and so on.
Methoxy Acrylate Fungicide ,pyrazole bacteria have a better therapeutic effect on brown spot disease.But azoxystrobin used in early maturing varieties may appear phytotoxicity, should be avoided use it.
Used pesticides:Methyl thiophanate,Mancozeb,Chlorothalonil and so on.
Note: spraying Bordeaux liquid is easy to produce fruit rust, should be used after bagging.
