In order to make decisions on spraying and giving priority to different blocks of fruit, it is very important to check spray history for each block and consider the kick back period for fungicides.
A variety of fungicide sprays with differing modes of action are available for this disease. When and how they are used depends upon their mode of action.
Maintain natural resistance (continued from last month)
The entire management program should be aimed at maintaining the trees’ natural resistance against diseases and pests so that no additional spraying is necessary.
Trees with too much vigorous growth, for example, are especially susceptible to black spot, mildew, aphids, mites, and codling moth.
The goal of fertiliser application in integrated production is to cover the nutrient requirements through natural cycles.
Soil analysis is the most important basis for the fertiliser dosage of phosphate, potassium, magnesium, boron and other nutrients.
Unbalanced nutrient application, and application of high rates of nitrogen fertilisers also have negative effects on vigorous growth and management of pests and diseases.
It is necessary to apply nitrogen during the phase of greatest demand and in the case of larger amounts, to distribute the amount over several applications.
If the amount needed is more than 60 kg/ha, it must be allocated in multiple applications.
This approach to pest management is one of the basic principles of Integrated Pest Management—saves money, saves environment.
Avoid products harmful to predatory mites
Products harmful to predatory mites should also be avoided. Treatments with dithiocarbamates must be reduced to a minimum and also the intervals between spraying with these products must be made longer.
When spraying with fungicides and miticides at the same time, the biological balance between pest and its natural enemies is disturbed.
In this case, the use of dithiocarbamates—used for apple black spot control—and other products harmful to beneficial insects, must be limited in order to guarantee the protection and promotion of predatory mites and other enemies of spider mites (spider beetles, minute pirate bugs, etc.).
In orchards where selected pesticides are used, beneficial insects can live and thrive. The inconspicuous species (i.e. chalcid wasps) often escape our attention.
The goal of Integrated Pest Management is to guarantee the economic success of the orchard using as little and as environmentally-friendly plant protection products as possible.
See this article in Tree Fruit Dec 2016
