The diamond back moth (DBM), Plutella xylostella (L.) is one of the most destructive pests of cruciferous vegetables like Cabbage, Cauliflower, Broccoli, and most preferred host is cauliflower.
DBM population becomes abundant during September to October and March to April.
Damage potential of DBM: Diamond back moth insect is resistant to many classes of insecticides and causes 50 to 80% loss in marketable yield.
Stages of Diamond Backed Moth [DBM]
- The eggs of DBM are whitish yellow, very small and 0.5 mm long and each gravid female can lay up to 164 eggs under field conditions
- Neonates will be dull white with light brown head.
- Fully grown caterpillars will be light green in colour measuring about 10 mm in length.
- The larvae are actively feed for 14 and 21 days before pupation.
- Larvae pupates in silken cocoon loosely spun by the caterpillar appears near the midrib on the upper surface of the l
- Pupa is light brown in color about 6 mm long.
- Moths are greyish coloured with a wing spread of 14 mm.
- The wing of male moths is up folded outward and towards their tips forming a row of three diamond-shaped yellow spots at the middle of the back.
- Adult longevity ranges from 6-13 days, females live shorter than males.
Organic Management of Diamond back Moth
Plant & animal derivatives or metabolites and disease causing pathogens are said to have insecticidal effect to control several classes of insects including Diamond back moth on cabbage and cauliflower. These agents may be used in organic farming to control many plants feeding insects.
Spinosad is metabolite extracted from the aerobic fermentation of actinomycete bacteria the Saccharopolyspora spinosa, isolated from soil. Commercially available Spinosad is a mixture of spinosyn A and spinosyn D metabolites of bacteria which have insect killing properties with stomach poison and organal nerve damage. Spinosad is said to have very low toxicity to mammals, natural parasitoids and predators for insects. Due to the unique and non-chemical nature the Spinosad may be used in organic agriculture pest control.
Neem oil is also an effective pesticides that may be used in organic farming. The azadirachtin metabolite of neem seed extract has detrimental effects on plant pests. The combination Spinosad and Neem oil have higher effect and longer efficacy in broad range of insects including diamond back moth larvae on Cabbage, Broccoli and Cauliflower.
Microorganisms which cause diseases in insects may be directly used on crops infested with insects in organic Farming. Bacteria BACILLUS THURINGEINSIS [Bt.] is sprayed on crops so that the insects consume Bt. bacteria, will be killed with toxins released by the Bt. bacteria, in the insect stomach.
Following spray combinations may be administered for controlling DBM on Cabbage, Broccoli and Cauliflower crops organically.
Spray - 1
Alternately every 10 days
Spray – 2
Things to be considered for effective control of DBM
- Grow two rows of mustard after every 25 rows of cauliflower/ cabbage as a trap crop at the time of planting. This traps 80-90% of DBM population and other pests. One row of mustard is sown 15 days before cabbage planting and the second row 25 days after planting of cabbage. The first and last rows of plots are also mustard.
K SANJEEVA REDDY,
Senior Agronomist, BigHaat.
Disclaimer: The performance of the product (s) is subject to usage as per manufacturer guidelines. Read enclosed leaflet of the product(s) carefully before use. The use of this product(s)/ information is at the discretion of user.
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