Latest Control Techniques and Methods Tutorial for Citrus Black-Skin Fruit

Many citrus or lemon growers are familiar with black-skin fruit. This is a serious disease that generally appears in summer or autumn, causing the fruit to taste sour and the skin to turn black, losing its commercial value and resulting in enormous economic losses. So how should citrus black-skin fruit be prevented and controlled? Let's find out together.

1. Causes

Citrus black-skin fruit is caused by damage from the citrus rust mite, also known as the rust spider mite, rust mite, or leaf-piercing gall mite. Adult mites, nymphs, and larvae pierce the fruit and leaves with their piercing-sucking mouthparts to suck out sap. When the oil cells of the fruit are destroyed, the overflowing oil is oxidized and turns brown to dirty black, so black-skin fruit appears. It also damages leaves, making them look as if they have been smoked. Once the fruit turns dark brown, the best control period has been missed. It not only causes large numbers of leaves to yellow and drop, weakening the tree's vigor, but also affects the yield of the following year.

2. Occurrence Pattern

The host range of the citrus rust mite is limited to citrus fruit trees. During its peak occurrence period, larvae, nymphs, and adult mites can be seen at the same time. The adults also read in summer and autumn, and in the second half of the year they move to spring shoots and their fruit to cause damage. In early May, they damage the underside of tender leaves of spring shoots; after leaf damage, the underside shows dark brown net-like patterns, and at the same time triggers a large amount of leaf drop. In mid-to-late May and early-to-mid June, they begin to damage fruit, and in July-September is the peak period, when fruit damage is severe. If high-temperature and high-humidity weather occurs, it is not conducive to rust mite reproduction; if high-temperature and drought weather occurs, rust mite damage worsens.

3. Control Measures

The rust mite is very small, initially white, later turning pale yellow. When the infestation is severe, mites and eggs appear in patches on leaves and fruit, so during control it is necessary to observe carefully, generally using a magnifying glass to inspect leaves and fruit surfaces. Once dust-like mite bodies are found, spray pesticide promptly for control. For the pesticide, lime sulfur mixture can be chosen; this is an effective agent for controlling rust mites. When spraying, first spray the inner and lower parts of the canopy, then the outer and upper parts of the canopy, focusing on the shaded sides of fruit and leaves. Spraying is best done at 10 a.m. and after 5 p.m. Spray carefully and thoroughly, so that leaves and fruit are moist but no liquid drips off. Generally spray 2-3 times in succession, with an interval of 7-10 days each time.

  The above is an introduction to the control techniques for citrus black-skin fruit. We hope it helps you. To learn more related knowledge, please follow us.