Prevention and Control of Citrus Diseases and pests in Summer

High temperature and humidity in summer is the season with the highest incidence of citrus diseases and pests in a year. During this period, if disease and pest control is not effective, it will seriously affect the cultivation of young branches and tips of citrus, affect the development of young fruit of fruit trees, and even cause a large number of fruit drop, so it is necessary to strengthen the work of disease and pest control in summer. According to the recent investigation of Yangqiao, Longhua, Shajing, Lantian and other township citrus orchards in this and Longmen stations, the main citrus diseases and insect pests are anthracnose, canker, skirt rot, leaf moth, red spider, wood louse, longicorn beetle and so on.

I. occurrence of diseases and insect pests

1. Anthrax: moderate and locally severe anthrax is expected to occur. According to our recent survey in some orchards of Yangqiao, the highest injury rate of tangerine leaves is 4.6%, with an average of 1.8%.

2. Canker: it is expected that the occurrence of oranges and oranges is moderate and mild, and that of orange varieties is moderate. Among them, Yang overseas Chinese orange leaf injury rate 3.6%, fruit injury rate 0.7%, disease index 0.12.

3. Skirt rot: moderate occurrence is expected. Recently, more cloudy and rainy days are conducive to the occurrence of the disease, of which Yang Qiao has the highest disease rate of 2.4%, with an average of 0.5%.

4. Leaf miner: the occurrence is expected to be moderate, and the occurrence is more serious in some orchards. Among them, the leaf injury rate of Yangqiao citrus is the highest 10%, with an average of 2.4%. Leaf miner adults are found on fruit trees and weeds in Longhua, Shajing and other orchards, of which the highest number of adults is 1.3 per 100 meters of weeds (slightly lower than that of the same period last year), with an average of 0.5. The first peak is expected to be from mid-May to early June.

5. Red spider: expected to occur moderately. According to a recent survey conducted by Longmen Station in Longhua, Shajing, Lantian and other places, the average number of red spiders per leaf in the orchard was 9.3, with an average of 2.6, a decrease of 82.2% compared with the same period last year.

6. Planthopper: moderate occurrence is expected. Among them, Yang Qiao has 3 adults and 8 nymphs per hundred shoots. Planthopper is the main insect that spreads citrus Huanglong disease and should be controlled. The second peak is expected to occur in the summer shoot germination period from May to June.

7. Longicorn beetles: moderate occurrence is expected. Among them, Yang Qiao found 3 adults and 8 eggs per 100 plants. Longicorn beetles occur one generation a year, and the spawning period is from the middle to the middle of May to the first and middle of June.

In addition, aphids, shell insects, whitefly, inchworm, butterfly larvae, rust spiders, beetles, scab, gum disease and so on also occurred in varying degrees.

II. Opinions on prevention and control

1. Strengthen field management: citrus fruit trees should be pruned in summer at the right time, and young trees should be smeared to control shoots. When more than 70% of trees in the garden and more than 70% of each tree have shoots, they should be uniformly placed and sprayed to control them. This is not only conducive to centralized eradication of various diseases and insect pests, but also greatly save production costs.

2. Chemical control. All localities should strengthen the systematic investigation of citrus diseases and pests, grasp the appropriate period for the control of major diseases and pests, timely classified control, rational mixed use of pesticides, and control chemicals should be used alternately, so as to slow down the drug resistance of pests and reduce the pollution of pesticides to the environment.

① anthracnose: you can choose 80% anthrax Fumi wettable powder 800x solution or 50% acetaminophen 600x solution or 40% polysulfide suspension (methomyl) 300x liquid or 80% essential wettable powder 600x liquid or 62.25% Xiansheng wettable powder 600x liquid and so on.

② canker: at present, we mainly control the prevention and control when the average transverse diameter of the fruit is about 2.0cm. With 0.5% Bordeaux solution or 77%, we can kill 2000 type 600x liquid or 50% Carinon wettable powder 600x liquid or 30% copper oxychloride 500x solution. In addition, spray medicine in time after each typhoon and rainstorm.

③ skirt rot: first scrape the diseased plant thoroughly, then apply 40% polysulfide suspension or Ruidu Manganese Zinc evenly to the diseased plant for 2-3 times.

④ leaf miner: 1.8% avermectin 3000 times solution or 20% gram moth 2000 times solution or 20% good year winter 2000 times solution can also control citrus aphids, wood lice, whitefly, inchworm, butterfly larvae and so on.

⑤ red and rust spiders: regularly check the insect situation and find that there are an average of 3 red spiders per leaf, 4 or 56% of the leaves on leaves or fruits with rust spiders should be sprayed in time, using 2000 times solution of 15% dacarine or 1500 times solution of 50% mites or 1500 times solution of 20% mites, etc.

⑥ longicorn beetles: first, to cut down the seriously damaged aging trees as early as possible to reduce the source of insects; second, to make use of the midday habitat characteristics of longicorn beetles to kill adults; third, to inspect the tree trunk from June to August and found that eggs and young larvae can be scraped and killed with a knife. Fourth, after the larvae are eaten into the xylem, the larvae can be killed with steel wire hooks, or 80% dichlorvos emulsion or 40% dimethoate emulsion 5-10 times, absorbed with skimmed cotton, stuffed into the mouth to kill the larvae.