Current Status and Prospect of Web Blight of Cowpea: A Review

Pulses in India have been considered as the poor man’s only source of protein. Among them Cowpea (Vigna unguiculata) is an important food legume which is also known as vegetable meat due to high amount of protein in the grain with better biological value on dry weight basis. Various factors viz., diseases and insect pests are mostly responsible for its low production. Among diseases, web blight caused by Rhizoctonia solani is one of the most important disease of cowpea. The web blight appears every year at varying intensity and causes heavy losses in yield. Web blight disease is most severe at seedling and vegetative stage. The disease is characterized by oval or spindle shaped brown black lesions having length ranging from 0.2-8 cm at soil level near collar region and girdling the basal portion of the stem and lesions developed by basidiospores of Thanatephorus cucumeris which are 2-4 mm in diameter, circular and appear as brown necrotic spots with light brown centre. Cob web like symptoms also noticed hence, the name web blight.

Use of narrow-band imaging in detection of nasopharyngeal carcinoma

Aim:To compare narrow-band images of nasopharyngeal carcinoma with those of normal adenoidal tissue.Method:Patients with a nasopharyngeal mass were evaluated using both conventional white light and narrow-band light. Biopsies were performed and Epstein–Barr viral serology was tested for all patients.Results:Thirty consecutive patients were recruited. Twenty-one patients had normal adenoidal tissue and seven had nasopharyngeal carcinoma. One patient with papillary adenocarcinoma was excluded. The features of narrow-band imaging in normal adenoidal tissue were: (1) a regularly arranged follicular pattern, and (2) each ‘follicle’ comprising a pale centre with surrounding dark periphery. The features of narrow-band imaging in nasopharyngeal carcinoma were: (1) absence of surface patterns (n = 7), and/or (2) ‘reverse’, haphazard follicular pattern comprising a dark brown centre and pale periphery (n = 3).Conclusion:Narrow-band imaging of the surface of adenoidal tissue and nasopharyngeal carcinoma appears to identify distinct, characteristic features as described. Narrow-band imaging may be a useful adjunct in differentiating normal adenoidal tissue from malignancy. Further studies are needed to evaluate its diagnostic accuracy.

Ramularia bistortae. [Descriptions of Fungi and Bacteria].

A description is provided for Ramularia bistortae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Polygonum bistorta, P. viviparum. DISEASE: Leaf spot of P. bistorta. Lesions on both sides, irregular, often angular or circular, dark purple-brown margin with light brown centre, size varies from 1-8 mm (usually 4-5 mm) diam., sporulation occurs on both sides of leaf. GEOGRAPHICAL DISTRIBUTION: Europe: Austria, England, Germany, Italy, Romania; North America: USA (Wyoming). TRANSMISSION: Not known, probably wind dispersal by air-borne spores.

Mycosphaerella musicola. [Descriptions of Fungi and Bacteria].

A description is provided for Mycosphaerella musicola. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Musa spp. DISEASE: Sigatoka of banana is the major leaf disease of this crop. Its conidial state has been compared with that of the similar (but more restricted and only recently described) disease caused by Mycosphaerellafijiensis (CMI Descript. 413, black leaf streak of banana; 48, 307i). A yellowish-green speck (< 1 mm long) becomes a yellowish streak 3-4 × 1 mm; this broadens and lengthens, has an ill defined margin and turns brown or rusty. The outline becomes more definite and the brown centre has a yellow to light brown halo, sometimes with a water-soaked border. In the fully developed spot (12-15 × 2-5 mm) the sunken central area is at first dark then becoming grey, with a dark brown or black border and sometimes a chlorotic halo. Coalescence of the spots can lead to the death of large areas of the leaf. In general, spotting is commoner towards the leaf apex and edges. Streak and tip spotting are caused by ascospore infection, mostly on the apical third of the leaf. Line spotting (mostly basal) is caused by conidial infection (45, 2189). The damage to the leaves detrimentally affects the physiology of fruit ripening (at lower levels of infection), reduces yield and increases the time from shooting to bunch maturity. GEOGRAPHICAL DISTRIBUTION: Widespread (CMI Map 7, ed. 6, 1969). TRANSMISSION: Water splash and air dispersal by conidia and ascospores, respectively. Conidiomata are probably more abundant than perithecia. Ascospores are released largely through rain over a wide temperature range. In Honduras the peak ascospore dispersal occurred at c. 0200 h (lower rainfall season) and at c. 1000 h (higher rainfall season). The conidia are the major source of inoculum.