What are the common pests and diseases in grapefruit cultivation?
What are the common pests and diseases of grapefruit? How should they be prevented and controlled? Please describe the following common pests and diseases of grapefruit and their control methods: I. Main diseases of grapefruit. The main diseases of grapefruit include citrus huanglongbing, canker, scab, and anthracnose; their control methods are the same as those for mandarin oranges and can be applied by reference. Canker is relatively serious in its harm to grapefruit...
What are the common pests and diseases of grapefruit? How should they be prevented and controlled? Please describe.
Grapefruit has the following common pests and diseases and control methods:
I. Main diseases of grapefruit
The main diseases of grapefruit include citrus huanglongbing, canker, scab, and anthracnose; their control methods are the same as those for mandarin oranges and can be applied by reference. Canker is relatively serious in its harm to grapefruit. Canker is caused by bacteria and mainly attacks new shoots, tender leaves, and young fruit, forming nearly round, suberized, rough-surfaced, yellow-brown canker spots 0.3-0.5 cm in diameter, causing leaf drop and fruit drop, affecting growth and yield, and reducing the external appearance and internal quality of the fruit. Control methods: give priority to prevention, adopt integrated management, strictly enforce the quarantine system, establish disease-free mother tree orchards, scion nurseries, and seedling-raising bases, and prevent diseased seedlings from leaving the nursery. Integrated measures should be adopted for control in affected orchards.
1. Thoroughly clean the orchard. After harvest, prune off diseased branches and diseased leaves, clear away diseased fruit and fallen fruit, and burn them on site. After cleaning the orchard, spray lime sulfur mixture comprehensively to eliminate overwintering sources of the disease.
2. During each shoot-flushing period, promptly control the insect pests that transmit the disease sources, such as citrus leafminer and citrus leaf beetle.
3. After each new shoot emerges (before self-pruning) and after flowers fade, spray once every 10, 30, and 50 days. Optional pesticides include Bordeaux mixture at 1:2:100 dilution, agricultural streptomycin at 600-1000 units per milliliter plus 1% ethanol solution, 50% zineb aqueous solution at 500-800 times dilution, 50% tecloftalam powder at 500-800 times dilution, etc.
II. Main insect pests of grapefruit
The main insect pests of grapefruit include mites such as red spider mites and rust mites, scale insects such as arrowhead scales and brown soft scales, citrus leafminer, and buprestid beetles.
Mite control methods: spray 73% propargite emulsifiable concentrate at 2000-4000 times dilution, 50% cyhexatin at 1500-2000 times dilution, or 20% dicofol emulsifiable concentrate at 800-1000 times dilution. For scale insects, during the larval occurrence period, continuously spray 40% omethoate emulsifiable concentrate at 1000 times dilution or 20% fenvalerate emulsifiable concentrate at 3000 times dilution 1-2 times. For citrus leafminer, when most new shoots have grown to 0.5-1.0 cm, begin spraying 25% deltamethrin at 2500-3000 times dilution or 40% isocarbophos at 800-1000 times dilution once every 5-10 days. For buprestid beetles, during the peak emergence period of adults and before they emerge from the holes, scrape off the dead bark on the trunk and apply a 1:1 mixture of 40% dimethoate emulsifiable concentrate and kerosene to the damaged areas; during the peak period when adults emerge from the holes, spray the tree canopy with 80% dichlorvos emulsifiable concentrate at 1000 times dilution or 90% trichlorfon at 1000-1500 times dilution.
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