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The disease i s seen at all crop growing stages. The fi rst symptoms appear at the time of emergence of seedlings, when the cotyledons are attacked. They become yellow and turn brown followed by wilting and drying of the affected seedlings. In the fi eld, the wilting symptoms appear in patches. First of all, the older leaves become yellow, loose their turgidity, wilt, turn brown and droop.

The disease is seen at 3-4 leaves stage. Scattered, irregular, yellowish patches appear on the upper surface of the leaves and stipules. On the corresponding under surface of these patches, a greyish violet fi ne cottony mildew growth is seen. Infected tissue soon dies and turns brown. The disease fi rst appears on lower leaves and later spreads to upper leaves.

Disease appears later part of the crop season mostly during blossoming period. The first sign of the disease is the appearance of small brown patches on the leaves mostly on basal leaves which starts from tip or margin of leaves and spread downwards or inward directions.

It is a very common disease found in all the onion and garlic growing areas. It mostly attacks the bulb as well as the seed crop. The infection or severity of the disease is more in Kharif crop causing 60% yield loss.

It is a very important and commonly found disease of chili which observed in field as well as in storage. It is also known as anthracnose disease which is mostly seen in tropical and sub tropical regions.

It is a very common disease of mango. It is otherwise known as blossom blight, leaf spot, twig blight or wither tip.

Citrus crop includes lime, lemon, sweet orange, mandarin orange, Kamala orange, grapefruit, malta and pomelo etc. The disease which attacks one species of citrus mostly attacks other species also.

The disease attacks all the growth stages of plant affecting all above-ground parts. Plant covered with powdery patches leads to distortion, malformation and discolouration of leaves especially young leaves. Powdery patches gradually turn to grey and fi nally dark colour. Affected fl ower fails to develop fruit. Young berries turn black, irregular in shape and develop cracks. Sometimes berries ripe partially and rot. Vines get wilted.

It is a serious disease of apple which not only reduces the quality and size of fruit but also cause premature fruit drop and defoliation. Fruit loses its marketability due to poor quality. It also reduces storage time and cause loss up to 70%.

The fi rst symptom of disease appears in early spring soon after leaves come out of buds. Affected leaves become distorted and fold over as tips directed backwards. The whole lamina puckered except tip and blistered. In some leaves, part of leaf show distortion. Blistered portions are thicker, softer than the normal leaf blade. The affected areas remain green for a while and gradually become yellow and fi nally turn reddish-purple in colour. 

It is known by different names such as Ramularia leaf spot, rust, bird’s eye spot, grey spots, and white spot. It mostly attacks leaves but can also attack fruit stalks and also fruits.

The symptom appears as numerous, circular, light yellow to dark yellow spots on both the surfaces of leaves but is more prominent on the upper surface. The spot may coalesce to form large, irregular patches and soon entire leaf turns yellow and dries. Affected leaves appear as reddish-brown in colour. Excessive spotting destroys green tissues and becomes weak and yield reduced drastically

The disease appears as tumour like swelling or galls on leaf veins, leaf stalks, peduncles, stems and on fruits. The galls on the vein give a swollen and hanging appearance to the leaves. These are elongated, looks glossy in beginning but later rupture to become rough and corky. When stems remain succulent, numerous tumours may form on them. In severe case, the plant may kill prematurely.

All varieties of rose are susceptible to this disease. It is an important disease of rose which causes a sharp reduction in number and size of fl owers.

Plant diseases are caused by different etiological agents like Fungi, Bacteria, Viruses, Viroids, Phytoplasmas, Rickettsia like bacteria, Nematodes, Algae and Protozoan parasites. To control these specific pathogens and the diseases caused by them, a specific group of medicine/chemical molecule is required.

Fungi are one of the major causes of crop damage which affect crop yield, quality and revenue. Therefore to control these fungal diseases, fungicidal crop protection products are used at different stages of crop growth. Many of our current fungicides produce excellent results with respect to efficacy, crop quality, food safety, and improved cost/profit ratios of agricultural production.

Fungicide which is effective only if applied prior to fungal infection is called a protectant, eg. Zineb, Sulphur. Protectant fungicides are prophylactic in their behaviour.

Actino-IronOG (Streptomyces lydicus WYEC)

Biological soil and seed treatment for Fusarium, Rhizoctonia, Pythium, and Phytophthora with added iron.

There are several fungicidal molecules available in the market, some of which are specific for certain diseases/pathogens while others are broad spectrum and can be used against a range of diseases. However, for proper control measures a knowledge of disease specific fungicide are very important. Ready-Reckoner for disease specific fungicide (Table 4) makes available the option for selection of alternative fungicide in the management of specific disease.

Development of fungicide resistance in a fungal disease pathogen is a major concern for some of the important diseases in their management. This can be overcome by designing of fungicide use strategies to manage the threat of fungicide resistance.