Sunday, April 27, 2014

Diseases of Apple: Collar Rot Management

This is in continuation to my earlier post on Diseases of apple: Collar rot Description. This disease is generally diagnosed wrongly for white root rot and we treat it for the same by drenching with carbendazim, that further worsen the situation and plant dies pre-maturely. If diagnosed with the symptoms explained in my previous post i.e. coffee brown colour and late bud break, more number of spurs, small and sparse leaves, it should be managed in holistic way

  1. Phytosanitation: Free water or flood irrigation high moisture content near the trunk are major pre-disposing factors for the disease to spread. So keep the cultivation area free of diseased material like diseased bark and roots, etc. The cleanliness reduces the primary inoculum of the disease causing agents. This simple principle should be followed as soon as the first symptom in the form of late bud break or purple veins appears on lower side of leaves. This is the best way to manage the diseases on small farms and helps in reducing the costs.

  1. Cultural Practices: Alter the environment in which disease is appearing i.e. high moisture level in the basin and nearby trunk. Add gravels and sand near the trunk, remove soil from graft union. Improve drainage from the basin area. Since this also removes the primary inoculum as well as modifies the environment for disease proliferation again without enhancing the cost to a greater level.

  1. Biological Control: Introduction of biological control agents in the soil e.g. Trichoderma viride, and its variants help the plant in fighting with plant pathogen and grow healthy with a little cost. If consortium of different soil inhabiting biocontrol agents is available it will help better in managing the disease.

  1. Chemical Control: Agrochemicals should be the last priority to manage the disease and that too after the proper diagnosis. As the application of a wrong chemical will not only worsen the situation but also pollute the soil and soil microflora. i.e. soil health. In turn increase the cost without preventing the damage caused by the insect-pests or disease. Different combiproducts have been reported to control the disease among these, combinations of metalaxyl + mancozeb, moxymate + mancozeb, and dimethomorph are very effective.
In my comng post I shall be discussing about white root rot of apple.