Chickpea
Of the 50 pathogens reported on chickpea from different parts of the world, 14 have been reported in Bangladesh (Ahmed 1985; Fakir 1983). The important diseases are wilt (Fusarium oxysporum f. sp. ciceri), collar rot (Sclerotium rolfsii), dry root rot (Rhizoctonia bataticola), and botrytis gray mold (Botrytis cinerea).
Wilt
Wilt is widespread in the chickpea-growing areas of Bangladesh. Although no precise information is available on the extent of damage by the disease a rough estimate of 10% loss has been considered to be a regular feature in the chickpea-growing states of India (Singh and Dahiya 1973). In Bangladesh, seasonal observations have shown a much higher incidence of the disease. The pathogen causes total or partial wilting. When split opens lengthwise the xylem portion of the taproot shows dark brown to black discoloration. The disease development is rapid at soil and air temperatures of 24 to 27°C while the infection remains restricted at ambient temperatures below 17°C (Grewal 1988). The causal fungus is soil as well as seedboxes. It can survive by forming chlamydospores in dead-plant debris for more than 5 years (Haware, personal communication).
Collar Rot
Collar rot is prevalent throughout the chickpea-growing areas of Bangladesh. Outside Bangladesh, the disease has been reported from several countries including India (Nene et al. 1984). It is, however, assumed that the disease exists in almost all tropical and subtropical countries where chickpea is grown. The disease can cause 4-84% loss in seed yield (Bakr and Ahmed 1988). It usually appears at the seedling stage although the incidence is not rare in older plants. The fungus damages the plant at the collar region at soil level. No discoloration of the root occurs. White mycelial strands along with mustard seed-like sclerotia are observed on the infected portion. The initial high soil moisture and the high soil temperatures (28° - 30°C) favor infection. Excess soil moisture after crop establishment suppresses the growth of the fungus. The nondecomposed organic matter near the soil surface provides the substratum for the rapid growth of the pathogen.
Botrytis Gray Mold
Botrytis gray mold is caused by Botrytis cinerea. It was first recorded in 1981. Outside Bangladesh, the disease is present in Nepal, India, Pakistan, Spain, Australia, Canada, Colombia, and Argentina (Nene and Reddy 1987). In 1988 the disease appeared in Bangladesh, devastating the chickpea crop throughout the country. The fungus forms gray or brown to light-brown lesions on leaflets, branches, and pods. The infected portion is covered with erect hairy sporophores giving a moldy appearance. Young growing twigs and flowers are particularly susceptible to the infection.
Lentil
Fifteen pathogens causing 17 diseases have so far been recorded in Bangladesh (Ahmed 1985; Bakr and Zahid 1986) but only a few are severe causing severe losses in yield. These are rust (Uromyces fabae), stemphylium blight (Stemphylium sp), Wilt (Fusarium oxysporum), and foot rot (Sclerotium rolfsii).
Rust
The disease was first recorded by Talukder (1974). It causes severe damage to crop almost all over the country. Losses depend upon the stage of the crop at the time of infection. The incidence of the disease varies considerably from year to year depending upon environmental conditions. High humidity, cloudy weather, and temperatures of 20-22°C favor disease development. The disease appears in areas with a dense canopy. Aecial cups are formed on stems, leaves, and pods followed by uredo and teleutopustules. Black or dark brown telia are formed on the stem late in the season. In severe cases, the leaves are shed and plants dry up prematurely.
Dry Root Rot
This disease was not common in farmers' fields but in recent years its incidence has increased considerably. Infection is scattered in the field. Affected plants dry up suddenly with a straw-colored appearance. The taproot is brittle and devoid of lateral and finer roots. The dead roots show shredding of the bark. Very minute dark-brown sclerotia can be observed with the aided eye below the bark and in the pith. The pathogen is reported to perpetuate on diseased plant debris and persists in the soil as a facultative parasite. The best solution is to use resistant cultivars.