In addition to yield losses, grain quality is also degraded, directly affecting its market and export value. The quality of flour from wheat mixed with infected grains and the finished product as "chapati". etc. Mitra reported the causative organism of Karnal bunt as Tilletia indica but later in 1944 Mundker renamed it as Neovossia indica. The blight pathogen belongs to the genus Tilletia = Neovossia, family Tilletiaceae, order Ustilaginales and class basidiomycotina.
Powdery Mildew of Wheat
Control: Based on analysis of powdery mildew samples on 11 Pm lines (differential set), 41 pathotypes were recognized in the country. The mycelium of the fungus is colorless at first, but later turns deep olive.
Yellow Ear Rot of Wheat
The seed infection can be eliminated by keeping the seeds in cold water for 4 hours followed by 10 minutes in hot water at 52 C. The nematodes turn the grains into galls and these galls together with the bacteria are harvested with the crop.
Ear Cockle Disease of Wheat
This is one of the few parasitic nematodes that infects above-ground parts of the plant. The pathogen produces various toxins such as piricularin and alpha picolinic acid etc. The blast pathogen has different physiological varieties.
Brown Spot Disease of Rice
Systemic fungicides, pyroquilon and tricyclozone, have been found to provide better control, as these fungicides disrupt melanin production in the appressorium, thereby inhibiting entry of the pathogen into the host plant. Control: Because disease promotes tissue discoloration, the phenolic prohibitins present in rice tissues are associated with disease resistance.
Bacterial Blight of Rice
The leaf disease phase is the most predominant form of the disease that occurs between the tillering and heading phases of the crop. When the affected leaves are cut off and immersed in clear water in a test tube, a cloudy ooze of the bacteria can be seen from the vascular bundles.
Sheath Blight of Rice
The perfect stages are Hypochnus sasakii Shirai = Corticium sasakii (Shirai) Matsumoto = Thanatephorus cucumeris (Frank) Dark. The pathogen belongs to the order Mycelia Sterilia of the subdivision Deuteromycotina. The pathogen can infect and survive certain weed hosts which can also serve as the source of inoculum for further spread of the disease.
Tungro Disease of Rice
Symptoms: Affected plants show leaf spot, which starts at the top of the leaf and moves down to the underside of the leaf (Fig.13). Disease cycle: Virus inoculum survives in rice or some wild relatives in the wild from where infection occurs in rice plants by the leaf vector.
Downy Mildews of Maize
Leaf Spots of Maize
Zonate Leaf Spot
Grey Leaf Spot
Brown Spot
Helminthosporium Leaf Spots
Maydis Leaf Spot
Turcica Leaf Spot or Leaf Blight
Control measures are the use of certified disease-free seeds, crop rotation and the use of resistant cultivars.
Sorghum Smuts
The membrane ruptured before the heads emerged and dark brown to black teliospores were exposed. The heads are completely covered with characteristic "witches' broom" (very small, coiled leaves that emerge from the heads of pistons at the nodes).
Grain Mold of Sorghum
Other measures such as collecting and burning torn heads before scattering the spores, crop rotation and deep plowing during summer months are useful to prevent damage by sorghum midge. During summer months, seeds are kept in plain water during the night for 4-10 hours and then dried in the sun for 10-12 hours.
Anthracnose of Sorghum
Downy Mildew or Green Ear Disease of Bajra
Control: Use of certified seed, eradication of infected plants, crop rotation for at least five years, and seed treatment with fungicides such as metalaxyl and spraying with the fungicide ridomyl) are effective in managing the disease.
Ergot Disease of Bajra
Initially, the third or fourth leaves from the top show drying and eventually the whole crown falls and dries up. Leaf cracking progresses downward as the disease progresses. Other measures such as crop rotation, using disease-free seed sets or treating them with fungicides, and collecting and burning affected parts after harvest are also useful for disease management.
Smut of Sugacane
Wilt Disease of Sugarcane
This facility is created for farmers at the site of sugar mills in India. If such canes are used for seed sets, they serve as the source of inoculum.
Early and Late Leaf Spots of Groundnut
The fungus has three strains based on the difference in the color of the mycelium and the size of the conidia. The affected leaves fall to the ground and cause infection in the next season.
Sclerotium Stem Rot of Groundnut
Disease cycle: Healthy plants initially infected by conidia lying in soil or plant debris or on contaminated seeds or husks. Secondary spread occurs through conidia carried by the wind or insects from lesions formed on the leaves of infected plants.
Seedling Rot of Groundnut
Control: To remove plant residues, self-sown groundnut plants, crop rotation, intercropping with arhar, early sowing and use of early maturing varieties, seed treatment and spraying with suitable fungicides like Benlate are useful to avoid infection to the crop. Control: Removal of crop residues, deep ploughing, harvesting at normal maturity and to avoid deep sowing and use of damaged seeds are useful to avoid infection to the crop.
Seedling Blight of Groundnut
These spots are irregular in shape and size with a dark border and gray center. Spots on young plants have a yellow halo. The disease is controlled by spraying 0.2% Dithane M-45 any other copper fungicide on days 30, 40 and 50.
Alternaria Blight of Mustard
White Rust of Mustard (Crucifers)
Sex organs are formed by mycelia within the intercellular spaces of systemically invaded tissues. The oogonium is globose, terminal or intercalary and is clearly defined into a periplasm and a single central oosper. The fertilization tube from the antheridium enters the oosphere by passing through the thin wall.
Downy Mildew of Mustard
Disease cycle: The pathogen is maintained through oospores that lie in the soil or on plant debris. A single conidium is formed at each branch tip and is oval, ellipsoid and hyaline, measuring 24-27 X 15-20µ. The conidium falls off and germinates through the lateral germ tube.
Sclerotinia Stem Rot of Mustard
Control: Cultural practices such as crop rotation avoiding cruciferous plants, eradication of weed hosts, deep summer plowing and destruction of crop residues are important. Control: The pathogen is soil borne and the sclerotia can survive in soil for several years, rotation of non-host crops of at least 4-5 years can be useful.
Bacterial Rot of Mustard
Chlamydospores are oval, single or in chains, terminal or intercalary and remain in the soil for a long time. The pathogen survives in soil as a saprophyte on dead host roots and other plant parts.
Phytophthora Blight of Pigeonpea
Control: The disease is controllable by cultural practices such as crop rotation, field sanitation, deep plowing in summer, mixed cultivation with sorghum, soil improvement with oil cakes, trace elements such as zinc and manganese, growing green manures in rotation. Control: The disease can be controlled by avoiding sowing in fields with heavy soil and poor drainage system. Selection of disease-free fields, soil solarization or summer plowing, and wide row spacing are good cultural practices for disease control.
Sterility Mosaic Disease of Pigeonpea
Other measures are seed treatment with ridomil or metalaxyl (0.3 g per kg of seed) and two sprayings with metalaxyl at a 15-day interval from the 15th day after germination, and the use of resistant varieties and the cultivation of pigeonpea on beds.
Rhizoctinia Blight of Soybean
The basidia of the perfect stage develop on a membranous layer of mycelium and have four strigmata, each bearing one basidiospore. Inoculum can be splashed and infect the stem and leaves of the parent plants and spread from leaf to leaf and plant to plant by contact.
Pod Blight and Seed Rot of Soybean
During the flowering period, the root of the affected plants shows brown to dark brown discoloration of the cortical area. The mycelium of the causal fungus produces branches at right angles to the main hypha, slightly narrowed at the main junction and has a transverse wall near the junction.
Seedling Blight in Soybean
Control: The infection can be minimized by plowing off crop residues, use of healthy seeds, crop rotation, seed treatment with fungicides like thiram + carbendazim (2:1) @ 3g/kg, spraying with benomyl @ 0.1%, sufficient potash the field and to grow moderately resistant fresh. Control: Measures such as using good quality seeds reduce or avoid stress that delays germination and seed treatment with fungicides are useful in managing the disease.
Bacterial Pustule
Soybean Mosaic Disease
Initially, the petioles and rachis along with the leaves show decline and within 2-3 days the decline of the whole plant occurs (Fig. 23). Affected plants can be pulled more easily than healthy plants as most of the lateral roots of infected plants become weak. Transverse sections of the basal region show bleaching of vascular tissue and fungal hyphae. The pathogen can produce resting spores known as chlamydospores that can survive in unfavorable conditions.
Ascochyta Blight of Gram
Grey Mould of Gram
Symptoms: Symptoms of the disease are necrosis and stem deformation and affected plants often die. Dark brown or black teliospores also develop in the same sorus in later stages. They develop mainly in stems and leaves.
Wilt of Lentil
The pathogen is present both inter- and intracellularly in vascular bundles of the host and produces macro- and microconidia therein. Symptoms: All above-ground parts of the plant are infected, and plants can become infected at any stage of their growth. The cotyledons and primary leaves show small reddish circular spots.
Vascular Wilt of Cotton
Bacterial Blight, Angular Leaf Spot or Black Arm Disease
The disease affects young crops and can cause yield losses of up to 40% if not controlled. The disease occurs in both tropical and temperate regions. The infection starts from the lower leaves and further spread of the disease occurs from conidia formed on these leaves.
Late Blight of Potato
Under favorable conditions of rain, followed by hot and dry weather, the disease spreads very quickly. Regular spraying with fungicides at an interval of 10-21 days, depending on the severity of the disease, should be done.
Black Scurf or Rhizoctonia Stem Canker
Amianan a Daya a Rehion: Kufri Naveen, Kufri Khasigaro, Kufri Himalini ken Kufri Sherpa Shimla Turod: Kufri Jeevan, Kufri Jyoti ken Kufri Muthu. Mabalin nga agbiag ti pathogen iti daga wenno kadagiti isuot iti napaut a panawen. Napateg ngarud ti sanitasion ken panangagas iti bukel tapno makontrol ti pathogen.
Common Scab of Potato
The primary inoculum comes from soil or infected tubers and further spread is through newly developed sclerotia. Soil treatment with PCNB 20-30 kg/ha or soil improvement with neem or margose cake 25 quantal/ha or with sawdust at the same dose, followed by the application of 120 kg nitrogen/ha at the time of planting, are effective measures for black scab control.
Bacterial Brown Rot or Wilt Disease of Potato
Disease cycle: The pathogen survives in soil, infected tubers and alternate cultivated and wild hosts. The pathogen enters the potato through suckers and also spreads through a contaminated knife while cutting tubers for sowing.
Virus Diseases of Potato
Potato Y Virus (PVY)
Potato Leaf Roll Virus (PLRV)
Since the virus is continuously transmitted, the use of insecticides to control the vector population can be particularly effective in seed crops. Disease symptoms, life cycle and control measures are given under potato early blight.
Wilt of Tomato
The disease is caused by the fungus Alternaria solani (Ell.& Mart.) Jones &Grout. The best control of the disease is to grow exotic varieties like Rutgers, Kanora and Roma etc.
Late Blight of Tomato
Root Knot Disease of Tomato and Brinjal
Control: Cultural practices such as crop rotation, fallow, sanitation, deep summer plowing, sunning and flooding are important to avoid nematode infestation. Organic soil amendment like addition of neem cake, karanje cake @ 25 quantals/ha reduced the incidence of root knot.
Damping Off of Tomato, Tobacco and Crucifer Vegetables
Using soil fumigation with nematocides is the best control method, but these chemicals are highly toxic and expensive. Control: Sterilization of soil by steam or dry heat will control damping off in nurseries.
Virus Diseases of Tomato
Pathogen: The causal virus is tomato mosaic virus, which belongs to the tobamovirus group. The virus particle is rod-shaped, usually straight, with a modal length of 300 nm and a width of 18 nm. The virus is transmitted by several species of aphids, including Myzus persicae, in a non-persistent manner.
Phomosis Blight, Leaf Spot and Fruit Rot
Control: Seed treatment with sodium hypochloride or any other chemical to remove external inoculum from seeds and use of resistant varieties are the only measures to manage the disease. Control: Control of aphid vectors and use of virus-resistant transgenic plants are the options for managing the disease.
Bacterial Blight of Brinjal
Disease cycle: The pathogen survives in soil on infested plant debris and also externally by seed. Disease cycle: The pathogen is externally seed-borne, which is the potential source of primary inoculum.
Mosaic Disease of Chilli
Virus Diseases of Chilli
The pathogen multiplies in the veins and spreads throughout the plant all the way to the seed. The pathogen spreads to and infects other leaves through splashing rain, wind and agricultural equipment.
Downy Mildew of Crucifers
The disease is found worldwide and most members of the cruciferous family are susceptible to black rot. After infection, the fungus multiplies and moves to xylem vessels, which are later plugged by the pathogen mycelium.
Downy Mildew of Cucurbits
Soil solarization for 2-4 weeks using impermeable plastic after the soil has been amended with ammonium sulfate is a good method of controlling the disease. Control: Spraying fungicides, zineb, mancozeb and tricop-50 have been recommended to control the disease.
Powdery Mildew of Cucurbits
The removal of infected canes and the eradication of wild gourds in the vicinity of vegetable plots are economic control measures in terms of the monetary value of the crop.
Cucumber Mosaic
Disease cycle: The virus inoculum is present throughout the year on one or the other crop or on weeds from where it is carried to a new crop by insect vectors. Growing cucumber in polyhouses is beneficial because the crop remains free from viruses, resulting in higher yield and quality of the fruit.
Powdery Mildew of Peas
Rust of Peas
Disease cycle: The pathogen completes its life cycle on pea, but other hosts such as cowberry, lentil, sweet pea and lathyrus also transmit the infection as the host and telial stages of the fungus and can serve as a source of primary inoculum for the pea crop. Further spread of the disease takes place via conidia, which are spread by rain, insects or contact with leaves.
Anthracnose of Beans
In seeds, the pathogen survives until the seeds are viable. The primary inoculum usually comes from seeds. The pathogen grows on cotyledons from where it spreads to other parts of the plant.
Virus Diseases of Beans
Disease cycle: Primary inoculum of the pathogen comes through infected seeds and further spread is by beetle vector, Henosepilachna dodecastigma. The symptoms of the disease are so noticeable that infected plants can be identified from a distance.
Powdery Mildew of Mango
Control: Control of the disease is very difficult because both the pathogen and the vector have a wide host range. It has now been established that the disease is caused by the fungal pathogen Fusarium moniliforme var.
Bacterial Blight of Mango
Disease cycle: The scab pathogen has two stages in its life cycle, the saprophytic stage which is found on dead leaves and where the pathogen overwinters. Secondary spread of the disease is developed by conidia after the primary infection occurs.
Powdery Mildew of Apple
Control: The prediction systems to warn possible time of disease appearance have been developed based on: I. Post-harvest spraying with 0.4% benlate or other fungicides will reduce perithecia formation on fallen leaves.
Stem Black of Apple
Stem Brown of Apple
Pink Disease of Apple
Fire Blight of Apple
Control: Pruning affected trees out of season and applying a 0.1% Bordeaux mixture can control the disease. Spraying 100 ppm streptomycin sulfate in 1% glycerin during flowering and flowering time provides effective control of the disease.
Collar Rot of Apples
Disease cycle: Sugary exudates that have large numbers of bacterial cells attract flies, bees and ants that carry the bacteria from infected to healthy trees. When flowering occurs, ants carry the infection from the sugary exudates that ooze from the cankers on infected plants.
Stem or Foot Rot of Papaya
Papaya Viruses
The virus is transmitted in a non-persistent manner by aphid vectors, Myzus persicae and Aphis gossypii. The genome of the virus is single-stranded DNA and is divided into two parts, DNA-A and DNA-B.
Anthrcnose Disease of Citrus
Control: Good cultural practices and proper handling of fruits to avoid damage and washing after harvest will reduce the disease. Post-harvest treatment with thiabendazole and storage of fruit below 10C will help control the disease.
Citrus Canker
In sandy areas, growing vegetables between rows of plants can be useful to avoid wind damage from wind-blown sand.
Citrus Decline
Citrus Greening Bacterial Disease
The bacterium in Asian countries is transmitted by a psyllid vector, Diaphorina citri, and the African bacterium is transmitted by another psyllid, Trioza erytreae. The disease is also transmitted by grafting and dodder, Cuscuta campestris from citrus to periwinkle (Catharanthus roseus).
Citrus Tristeza Virus Disease (CTV)
Disease cycle: Inoculum of the bacterium is available in infected citrus trees from where the vector can carry the infection to healthy plants. Control: Control of the vector population, reduction of inoculum sources by pruning affected branches or uprooting affected trees, using disease-free budwood for propagation and if possible using disease-free or vector-free nursery areas are important preventive methods.
Indian Citrus Ringspot Disease
Citrus Yellow Mosaic
Citrus Exocortis Disease
Control: One spray of lime sulfur before bud break and a second spray in the fall is effective in eliminating the disease.
Brown Rot of Peach
Peach Scab
The fungus can invade the trunk and roots through tunnels drilled by the larvae of Coelosterna beetles.
Stem Canker of Guava
Guava Anthracnose
Disease cycle: In countries where Cleistothecia are formed, inoculum is carried from season to season by cleistothecia.
Downy Mildew of Grapes
A leaf spot disease caused by a fungus, Phavophleospora indica Chinnappa, is known to occur on sapota in South India, but the sooty mold disease is economically more important. Leaf rust is caused by Phakospora zizyphivulgaris, ranging from mild to severe on all commercial cultivars in Punjab.
Leaf Spot
The causative agent of sooty mold is non-pathogenic and develops as a saprophyte on. The causative agent survives in the host's tissues throughout the year, and thus an inoculum is also available for new infections.
Fruit Rot
The pathogen is a soil inhabitant, attacks the roots and spreads upwards to the basal part of the stem causing wilting of plants. Other plants can be replaced by a protective coating on the trunk with Bordeaux paste and also drenching the soil around the trunk with Bordeaux mixture.
Pink Disease
Pathogen: The disease is caused by a viroid pathogen belonging to the potato finger tuber viroid group. The pathogen is experimentally transmitted by high-pressure injection into germinating walnut shoots.
Phytoplasmal Diseases of Coconut Palm
There are eight to ten years between the appearance of the first symptoms and the death of the palm. The disease is caused by a phytoplasm, but no vectors or other means of spread are known.
Bud Rot and Fruit Rot Fungal Diseases of Coconut
If the pathogen is able to produce many races, the monogenic resistance in the host may break down and the host may become susceptible to one or more of the newer races of the. This type of resistance is based on the interaction of protoplasts of the host and the pathogen.
