Disease and pest of cucurbitaceous crops
(A)Insect pest of cucurbitaceous crops ;
It is a most serious insect pest of cucurbits. The larvae and adult of this pest cause damage by eating away the young leaves and flower at the seedling and flowering stage respectively. The grub bores into the roots and fruits lie on the ground and pupate in the soil.
(1) Hand-picking and dusting kerosinized ash is the most common method of controlling this pest.
(2) Spraying the crop with Malathion 50 EC@500 ml. or dimethoate 30 EC 500 ml or methyl demeton 25 EC@ 500 ml/ ha
2. Fruit fly (Dacus cucurbitae coq.)
The maggots of this pest bore into the fruit and feed on the pulp result of which it starts rotting.
(1) Collection and destruction of all infested fruits in the field will help in minimizing the damage to the crop.
(2) Dusting the crop with Malathion or Dipterex powder in the affected field will help in controlling adult fly.
(3) Use of bait traps prepared from protein hydrolyzate @ 450 gm, malathion or Dipterex water dispersible powder (25 percent) @ 450 gm and water @ I gallon is most effective in controlling of this pest.
A whitish-green semi looper that cuts the leaf from the edge and makes a nest with the cut portion on the leaf and pupates inside the nest.
(2) Spraying the crop with Malathion 50 EC or Dichlorovos (Nuvan, Vapona, etc.) @ 2 ml per liter of water can control this pest.
The beetle and grubs feed on the leaves and other tender parts leading a considerable reduction in the yield
Tiny white superficial spots appear on leaves and stem and they become powdery on enlarging. Due to the attack of this discase, premature defoliation occurs and plants remain stunted in growth. The fruits too do not set or remain smaller in size
(1) This disease can be controlled by dusting sulphur (sulfex), or spraying Karathane or Morestan @ 2 ml per liter of water.
(II) Systemic fungicides Nimrod at 0.05 percent, Saprol at 0.1 percent, Calixin at 0.04 percent, and Benlate 0.05 percent gave better control of powdery mildew in cucurbits.
C.O.: Pseudoperonospora cubensis.
Purplish spots appear on the lower surface and yellow spots on the upper surface of leaves; fruits do not mature or do not attain the right flavor.
Application of fungicidal spray (such as Dithane Z-78. Dithane M-45. Blitox etc.) once a week helps to control this disease.
C.O. : Collectotrichum lagenari
Watermelon, muskmelon and cucumber is mainly affected by this disease. Light brown spots are formed on leaves which tun
and then to red, and the leaves present a scorched appearance. Circular oval sunken lessons develop on the disease infected fruits and the fruits rot later on.
Crop rotation with the non-cucurbit crop, use of disease-free seeds, seed treatment, and spraying or dusting of fungicides are the recommended control measures of this disease.
4. Fusarium root rot
C.O. : Fusarium solani & F. cucurbitae.
Sudden midseason wilt; the base of the stem becomes dark brown, with a soft, mushy cortical wilt; fruits rot; young seedling damping off.
Crop rotation and seed treatment with hot water at 55°C for 15 minutes followed by treatment with mercuric chloride (1 in 1000) are the recommended control measures for this disease. 5. Mosaic
Mottled leaf with roughened surface occurs. The green color is completely lacking in fruit. In severe cases, the plants are yellow and dwarfed and bear little or no fruit Aphids transmit this disease.
Growing resistant variety and spraying the crop with Dimethoate (Rogor30 EC) or Methyl Parathion (Metacid-50 EC) or Oxydomiton methyl (Metasystox-25 EC) @ 1 ml per liter of water for controlling the insect vector are the recommended control measures of this disease.