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Bean fly

Ophiomyia phaseoli
  • It is essential to control bean fly during the first four to five weeks after germination as it causes high economic yield loss in the seedling stage, especially during the dry season:
  • Plant early in the season, 3-5 days after the onset of the rains
  • Mulch with dry banana leaves, grass, rice straw and other similar plant straw to promote root development and enhance tolerance to maggot damage
  • Don't plant leguminous crops next to each other such as common beans, cowpea, soybean, mung bean and peas
  • Ridge up the soil around the plants to cover the roots 2-3 weeks after germination to allow roots to grow more quickly
  • Encourage natural enemies presence in the fields by planting flower stripes and by not using pesticides
  • Remove and destroy crop residues and all plant parts with symptoms of damage by the bean fly as maggots and pupae live in the bean stems.
  • Remove and destroy volunteer crops
  • Frequently irrigate to reduce water stress and strengthen plant to better tolerate the bean flies
  • Crop rotation with non leguminous crops
  • Avoid overlapping bean crops in the season to reduce build-up
  • Additional relevant crops: cowpea, soyabean, pigeon pea, common bean, mung bean, peas
  • Look for small black flies of 2 mm on bean leaves from plant emergence up to 2-leaf stage of plants
  • Look for tiny yellow feeding and oviposition punctures on the basal portion of the upper side of leaves
  • Stem: Search for thickening of the stem at soil level which is made by the the fly larvae feeding inside. Upon cutting the stem open, a brown or dark feeding area of damaged tissue can be seen just underneath the epidermis. This portion will contain larvae and pupae.
    • Whole plant: yellowing, wilting, stunting and dying of young plants (2-3 leaf stage)
  • Look for tunnels at the base of the leaf blades, and in the stems. Examine the underside of leaves for silvery or black tunnels
  • Take control measures when 5-10% of the plants are infested
  • Uproot and burn withered and dead infested plants to kill the larvae and pupae
  • Spray using neem-based products early in the morning or late evening on the plants
  • The larvae are inside the stems and cannot be reached by sprays. Seeds can be preventively coated with pesticides that enter germinating plants, and can protect from bean flies. Do not coat seeds yourself; buy them coated. Do not use treated seeds as food or feed.
  • When using a pesticide, always wear protective clothing and follow the instructions on the label.
  • Azadirachtin based-products (neem) to parlty control adult bean fliesby foliar sprays. Repellent, insecticidal, antifeedant and anti-egglaying pesticide.
  • WHO class U. Product unlikely to present hazard under conditions of normal use. Larvae moulting disruptor; also inhibits egg laying, has antifeedant effects; p.h.i.3 d; r.e.i. 1 d. No more than 1 spray when flowering. Toxic to bees + aquatic organisms.
  • Seeds coated with Anthraquinone + Imidacloprid + Metalaxyl
  • WHO class II. Imidacloprid should be avoided when crops are flowering
  • Apply Dimethoate based product to manage severe infestations
  • WHO class II. Treat seedlings about 3-4 days after emergence and and repeat after 7 days and possible 14 days if the infestation is severe. Apply 20mls/15 litres knapsack. PHI is 7days
AUTHOR(S): CABI, Patrick Beseh (PPRSD)

PRODUCED BY: Plantwise

©CAB International. Published under a CC-BY-SA 4.0 licence.