Spices and Condiments (1+1)

Pests and diseases

Pests
Aphids (Hyadaphis coriandri; Myzus persicae)
The attack of aphids usually occurs at the time of flowering. This insect is easily controlled by a number of insecticides (0.15% Dimethoate at 10 days interval). However, the use of these insecticides after the crop has started flowering kills the bee population, which affects pollination in the crop. The varieties, RC-15 and Rumanian exotic EC-69 are found to be resistant to aphid attack. Whiteflies are also reported to cause damage to the crop. Red mites (Petrobia latens), weevil, stink bugs (Nazara viridula and Agonoscelis nobilis), leaf eating caterpillars (Spodoptera litura and S.exigua), white fly (Bemisia tabaci), etc., are found on the plants.
A chalcid fly, Systole albipennis, has been reported to damage the fruits. A foliar application of 0.03% Phosphomidon or Dimethoate or Methyl dematon (0.05%) controls the leaf eating caterpillars, while red mites could be controlled by a foliar spray of 0.3% Dicofol or sulfex, 2-3 times at 10 day intervals. Other pests attacking coriander are thrips Scirtothrips dorsalis, Thrips tabaci and cut worms. The other stored product pests include Stegobium panicum, Lusiderma serricornai, Rhizopertha dominica, Cribbium psoylloids, Trigoderma granarium, Attagenenus fasciatus and Tribolium casteneum.
Keeping the moisture level in the grain below 11% is a prerequisite for discouraging these storage pests. Exposing the grains to temperatures of 50, 60, 70, 80 and 100°C for periods of 120, 60, 45, 25 and 15 minutes, respectively, reduces the incidence of storage pests. Fumigation with sulphur dioxide before storage is effective in arresting the storage pests. Other fumigants like Phosphine, Ethylene Dibromide or Methyl Bromide are also effective when used at the rate of 1.0-1.38 mg/litre.

Diseases
Wilt (Fusarium oxysporum f. Sp. coriandrii)
This disease inflicts heavy losses in all coriander growing areas. Wilt infection occurs in the roots and drooping, yellowing, wilting and drying symptoms are expressed in the aerial parts. Though no direct control measures are available against it, preventive measures like the use of disease-free seeds, seed treatment, use of resistant varieties, crop rotation and deep summer ploughing may help in reducing the wilt incidence.
Seed pelleting with Trichoderma viride (formulation with CFU 106) @ 4 g/kg of seed and neem cake application @ 150 kg/ha followed by a foliar spray of Hexaconazole (0.05%) helps. Seed dressing as well as oil drenching with Carbendazin (0.2%) or Thiophenate methyl on the 25th, 40th and 55th day after sowing are recommended. T. harzianum and Pseudomonas fluorescens could also be used for biocontrol. The wilt tolerant cultivars, Rcr-41, Rcr 4, GC 1 and 2 and Sindhu, should be grown in wilt-affected plots.
Powdery mildew (Erysiphae polygoni)
This disease is characterised by the appearance of a whitish, powdery mass on the leaves and stem. It is severe in the initial stages of the crop, arresting seed formation. But in case of its occurrence at later stages, the seeds produced will be of poor quality and the total quantity is also reduced. This can be effectively controlled by repeated spraying of Wettable sulphur at 0.3% concentration or 0.1% Karathane once at the time of disease infestation and 10 days later with Carbendazim (0.1%) or Dinocop (250 mVha) or dusting of Sulphur at 20-25 kg per hectare. Eco-friendly techniques of using 5% onion leaf extract as a foliar spray thrice also keeps the disease under check. The disease-tolerant lines like Sindhu, Swathi, CO-3, GC-1 and GC-2 could be used.
Blight
This disease is caused by the fungus Alternaria poonensis. The symptoms include the appearance of dark-brown spots on the stems and leaves. Spraying with 0.2% Carbendazim or Mancozeb 20 days after the grain set effectively controls the disease.
Stem gall (Protomyces macrosporus)
It is difficult to control stem gall by any of the fungicides. The Karan (UD 041) variety is found to be highly resistant to this disease under field conditions. Crop rotation is recommended to reduce the incidence of the pest. However, to keep the disease under check, seed treatment with Thiram 2.5 g/kg of seed or Carbendazim 1 g/kg of seed before sowing is followed. Spraying of Bayleton or Systhane (0.4 m1/1 of water) and a repeat spray after 20 days is recommended.
Stem-rot caused by Sclerotinia sclerotiorum, root-rot (Rhizoctonia solani) and grain mould (Altemaria, curvularia and Helminthosporium sp.) have also been reported. The grain mould infestation can be reduced by spraying 0.1% Carbendazim twice at grain set and after 15 days. Cilantro dwarf is a new disease reported from Brazil and the disease is caused by the nematode Rotylenchulus reniformis. The root knot nematode Meloidogyne incognita is also reported to cause damage to the crop.