Saturday, March 19, 2011

Brinjal diseases

Phomopsis blight attacks the stems of eggplant,
causing plants to wilt.The disease can also penetrate into fruit, creating a soft rot.
To control Phomopsis, select resistant varieties, sow pathogen-free seeds,
rotate crops, and spray with fungicides. Mulching and furrow irrigation will reduce infection caused by water and soil splashing. 

Eggplant suffers from several soil-borne diseases including Damping off,
Bacterial wilt, and Verticillium wilt. Damping off fungi (Pythium, Phytophtora
and Rhizoctonia) attack germinating seeds, creating lesions on the stems and
later the collapse of seedlings. Soil sterilization and seed treatment are
recommended control practices.

Bacterial wilt is very destructive, especially in the hot, wet season.
Plants wilt and die suddenly. When newly infected stems are cut crosswise
and placed in water, an ooze appears. Sow resistant varieties, rotate with non-Solanaceous crops, use raised beds for improved drainage, and graft 
plants onto resistant rootstocks. 

Verticillium wilt causes stunting and wilting of plants. Leaves turn yellow
along the margins, later turning brown and wilting. A lengthwise cut of the
infected stem shows dark-brown discoloration in the vascular tissue.
Soil sterilization and crop rotation with non-Solanaceous crops are
recommended. Grafting eggplants on suitable rootstocks also minimizes
the disease infestation. Use resistant varieties.
Other diseases on eggplant include Southern blight,
Alternaria and Cercospora leaf spot, and several viruses.

Numerous insects attack eggplant; only the most significant pests are mentioned in this tutorial. With the exception of the Fruit and Shoot Borer, these insects are controlled by weekly applications of insecticides during periods of infestation.
Shown are photos of the pests. Click on each pest for a close-up and photos of the damage it causes.

borer in fruit
Fruit and shoot borer is a very destructive in S and SE Asia. The larva bores inside the terminal shoots, resulting in the withering of the shoots. It also bores into the young fruit and feeds inside which makes the fruit unmarketable. Several insecticides control this borer, but numerous sprays are needed. Rotation of crops and the prompt destruction of damaged shoots on a community-wide basis are recommended as part of an overall IPM strategy.

Thrips attack eggplant mostly during the dry season. They cause browning of leaves, especially on the lower leaf surface, and the scarring of fruit. 

Leafhoppers feed mainly on the underside of eggplant leaves, causing yellow patches on the foliage. Certain species also transmit mycoplasma-like diseases, such as little leaf disease. Fruit setting is adversely affected by the infestation.

Aphids feed on the juices within leaves and stems. Black sooty mold develops on the sugary excretions of the aphid. This sooty mold covers the plants, thereby reducing photosynthesis and weakening the plant. Aphids occur in the cool dry season.
epilachna beetle Epilachna beetles feed voraciously on the leaves and tender parts of eggplant. They cause serious damage during their larval stage and when they appear in large numbers. As a result of their feeding, skeletonized patches develop on leaves. Later, the leaves dry away.

high quality eggplantHigh quality eggplant is firm, heavy (in relation to size), glossy with a desirable color, and free of cuts and scars. Once the color of the skin begins to dullen, the seeds darken and the flesh becomes spongy and bitter.
Harvesting is done by hand using a sharp knife or clippers, leaving the calyx attached to the fruit. Harvest once or twice a week.
Yields are commonly in the range of 30 to 40 tons/ha. Six to twelve marketable fruits may be expected per plant for the large-fruited varieties, weighing 300-400 gm each. The elongated varieties may produce twice as many fruits, with individual fruits weighing 100-150 gm each.

packed eggplantEggplant does not have a long storage life and should be marketed immediately after harvest. Fruits are generally sorted by size and color, and packed into either baskets or cartons. They are handled and packed carefully to avoid damaging the skin.
Eggplant can be stored safely for 7-10 days at 7-10°C and 90-95% relative humidity. It is subject to chilling injury when stored at temperatures below 7° C. Symptoms of chilling injury are pitting, surface bronzing, and browning of seeds and pulp.

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