What are the control methods for citrus canker in Orah mandarin?

Citrus canker is one of the most common diseases of Orah mandarin, mainly damaging new shoots, young leaves and unripe fruit, usually causing leaf drop, fruit drop, and even dieback of shoot tips, weakening the tree vigor. So what are the control methods for citrus canker in Orah mandarin? There are actually three main types of methods, namely agricultural control, chemical control and physical control.

I. Agricultural control

1. Regionalize the variety layout and avoid mixed planting of different varieties. Mixed planting of different varieties leads to unsynchronized shoot periods, prolonging the susceptible period of the orchard.

2. Control summer shoots. In orchards with extremely severe incidence, prune off the summer shoots of young trees, keeping only spring and autumn shoots. Clear the orchard first, then let the shoots emerge.

3. Keep the orchard clean to reduce the source of infection. Prune in winter, cutting off diseased, pest-infested and weak branches to reduce the source of infection; in severe cases, diseased branches and leaves can be pruned off directly.

4. Control pests to prevent disease. Damage by pests such as the citrus leafminer and leaf beetles often provides favorable conditions for the spread and entry of the pathogen, so timely control of these pests can reduce the disease.

II. Chemical control

1. Prevention at the flowering stage. Spray Bordeaux mixture once each before flowering and after petal fall (ratio of copper sulfate, lime and water is 0.5: 1: 100). During the summer shoot and autumn shoot periods, spray Bordeaux mixture twice per shoot (ratio of copper sulfate, lime and water is 0.5: 1.5: 100).

2. Prevention in extreme weather. Spray before and after strong winds and heavy rain; otherwise, spraying after the pathogen has entered often gives poor results.

2. During shoot emergence, for seedlings and young trees the focus is on protecting the shoots: spray once each 20 to 30 days after each new shoot emerges (or when the new shoot is 1.5cm long) and when the leaves have just turned green, and for summer shoots spray once more at an interval of 7 to 10 days; for adult trees the focus is on protecting the fruit, spraying once each 10, 30 and 50 days after petal fall.

3. Agents used at the early stage of the disease. Copper hydroxide, basic copper sulfate, thiodiazole-copper, copper acetate, copper oxychloride, kasugamycin, copper quinoline · kasugamycin, zinc thiazole, etc., must be used in rotation.

III. Physical control

1. Plant windbreak forests to block the spread of the virus

2. Cover with plastic film (shelter from wind and rain) to isolate the virus

3. Use mineral oil and agricultural synergists to protect new shoots from infection and damage by the pathogen.

Citrus canker in Orah mandarin is best controlled at the early stage of the disease; never wait until it has covered a large area before treating it, as by then it may already be too late and will affect its healthy growth.