Diseases and Management of Crops under Protected Cultivation
Diseases and Management of Crops under Protected Cultivation
Diseases and Management of Crops under Protected Cultivation
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(<strong>Diseases</strong> <strong>and</strong> <strong>Management</strong> <strong>of</strong> <strong>Crops</strong> <strong>under</strong> <strong>Protected</strong> <strong>Cultivation</strong>)<br />
Limitations<br />
‣ Chemigation requires considerable management input <strong>and</strong> personnel training<br />
‣ Chemigation requires a change in management techniques<br />
‣ Some chemical may react with irrigation system components<br />
‣ Additional equipment may be required for chemigation<br />
3. Selection <strong>of</strong> chemicals for chemigation<br />
Herbicide Application<br />
• Weed geminates in the top 25-50 mm <strong>of</strong> soil.<br />
• Therefore, application should be such that herbicide should reach to this depth, not<br />
beyond.<br />
• Sprinkler are the most widely used irrigation system for the application <strong>of</strong> herbicides<br />
• Spray emitters or <strong>under</strong> tree irrigation system are preferred over drip / trickle irrigation<br />
• Application <strong>of</strong> nematocides through drip irrigation have been very successful<br />
Selection <strong>of</strong> herbicides depends on:<br />
o Solubility in water : high - better<br />
o Volatility : Low – better<br />
o Adsorption : to Organic matter <strong>and</strong> clay should be low<br />
Fungigation : Application <strong>of</strong> fungicides through sprinkler irrigation<br />
• Centre pivot system : More effective – uniform coverage<br />
• Travelling / rain gun : Less effective – non uniform coverage<br />
• Coverage = f (formulation, amount <strong>of</strong> water <strong>and</strong> uniformity <strong>of</strong> irrigation)<br />
• For effective foliar application use a formulation that is not easily washed <strong>of</strong>f <strong>and</strong> use less<br />
water<br />
• If soil application is desired use formulation that will wash <strong>of</strong>f to a great extent <strong>and</strong> deposit<br />
the majority <strong>of</strong> the chemical on the soil <strong>and</strong> use more water per unit area.<br />
Insecticides:Application <strong>of</strong> insecticides through irrigation system depends on the :<br />
– Nature <strong>of</strong> insecticides<br />
– Special needs <strong>of</strong> the crop at various growth stages, <strong>and</strong><br />
– Efficacy <strong>of</strong> the insecticide<br />
• Insecticides can be injected undiluted or they can be diluted with water or oil to a volume<br />
necessary for calibrating within the range <strong>of</strong> the pump.<br />
• For many insecticides, mixing with an oil before injection can improve efficacy <strong>and</strong> residual<br />
control<br />
• Oil carriers should control no emulsifiers<br />
• Studies have shown that insecticide formulation best suited for chemigation are those<br />
insoluble in water <strong>and</strong> soluble in oil<br />
• LEPA ( Low Energy Precision Application) centre pivot system modified for chemigation (<br />
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