How is the citrus black fruit formed? How to prevent and cure it?

Many farmers who have planted citrus, lemon and grapefruit have had this experience: in summer and autumn, the peel of these fruits will turn black, commonly known as "black peel fruit". This kind of fruit is small, sour and black, which greatly loses the interests of growers. Let's take a look at how the citrus black peel fruit is formed. How to prevent and cure it?

First, how is the citrus black fruit formed?

Citrus black peel fruit is caused by citrus rust wall lice (also known as citrus rust spider, rust mite, gall mite). Adults, nymphs and young mites of citrus rust wall lice use piercing mouthparts to stab fruits and leaves to absorb juice. when the oil cells are destroyed, the spilled oil is oxidized to brown to dirty black, which farmers call "oil peel tuo" and "oil skin mandarin". The back of the damaged leaves is dark brown and seems to have been smoked, and the stain cannot be erased (the mildew layer infected with soot can be erased). When the citrus fruit (or leaf back) is dark brown, the best time for control is missed. Rust wall lice damage citrus fruit trees, but also cause a large number of withered and yellow leaves, weaken the tree potential, and seriously affect the next annual yield.

Second, how to prevent and cure the black fruit?

Recognizing the causes and development characteristics of this "black skin fruit", the next step is to introduce the prevention and control measures that fruit farmers are most concerned about. Because the body of the rust wall louse is very small, white at first, and then yellowish, there are worms and eggs on the leaves and fruits when they are serious, so in the initial observation, the leaves and fruit surfaces should be observed with a magnifying glass, with emphasis on the back of the leaves. If dusty insect bodies are found on the surface of individual fruits, chemical control should be carried out immediately. In order to control the rust wall lice, the inside and lower part of the crown should be sprayed first, and then the outside and upper part of the crown should be sprayed, with emphasis on the shady side of the leaf back and fruit. The suitable spraying time is before 10:00 in the morning and after 5 p.m. Spray should be careful, careful, spray amount to leaves, fruit moist but no drop is appropriate, generally spray 2 times 3 times, each time 7-10 days.