Inhibition of mycelial growth and sporidial formation in the wheat pathogenNeovossia indica by a polyamine biosynthetic inhibitor

DL-α-Difluoromethylornithine (DFMO), a specific suicide inhibitor of the polyamine biosynthetic enzyme ornithine decarboxylase (EC 4.1.1.17), strongly inhibited mycelial growth and sporidial formation of the wheat pathogen,Neovossia indica, in vitro, while DL-α-difluoromethylarginine (DFMA), the analogous suicide inhibitor of arginine decarboxylase (EC 4.1.1.19), did not. The inhibited mycelial growth and sporidial formation were not only restored by putrescine (polyamine) addition, but were actually enhanced in the putrescine + DFMO cultures. Besides altering mycelial growth and morphology, DFMO also reduced the cell size drastically. The inhibition of fungal polyamine biosynthesis is discussed in relation to selective control of plant disease.     

Studies on the systemicity of [14C]metalaxyl in cowpea (vigna unguiculata (L.) walp.)

[¹⁴C]metalaxyl applied to seeds, roots and leaves of cowpea was readily taken up by all plant parts and a major fraction of it was retained within the treated leaves and seeds but not in the roots. The fungicide exhibited ambimobility inside the plant. When applied to the middle of leaflets, metalaxyl mobilised towards proximal and distal parts of the leaflet. Intraleaflet movement seemed to result from translocation through veins and diffusion through cell walls and intercellular spaces. Accumulation of metalaxyl at tips and margins of primary leaves followed application to roots. Metalaxyl was readily extracted from most plant parts except cotyledons and only 0.8% of the fungicide applied as a seed treatment was recovered from 50-day-old plants.     

Ovipositional response ofHelicoverpa armigera to different cotton genotypes

The ovipositional response ofHelicoverpa armigera (Hübner) to different cotton varieties and species was studied under caged conditions. Maximum oviposition (51.6 eggs/female) was recorded on LH 900, a variety ofGossypium hirsutum, and minimum oviposition (3.0 eggs/female) on G 27, a variety ofG. arboreum. Oviposition, in general, was low (3 to 6.5 eggs/female) onarboreum cottons as compared withhirsutum. Of the number of factors found to affect the oviposition ofH. armigera, the trichome length on the upper surface of the leaf, rather than the density, was positively correlated (r = 0.687*). Among different months in the cropping season, oviposition was maximum (552.7) during April. Oviposition was higher on leaves than on other plant parts.     

The Pattern of Enteroviral Infections in a Herd of Swine

Twenty-six pigs from four litters in a healthy herd of swine were examined periodically for the fecal excretion of viruses by the use of porcine kidney cell cultures. Viruses were initially isolated from all pigs between 34 to 64 days of age. The pigs within each litter began shedding virus in their feces approximately at the same time, usually within one week, and the type of virus initially recovered was usually the same. Subsequently, waves of infection with different enteroviruses appeared to occur during the observation period of six months. At least six antigenically different viruses were isolated from this herd over a 26-month period. Most, if not all, of these viruses were considered to belong to the enterovirus group. No disease was associated with these enteroviral infections.

The colostrum and milk of sows contained significant amounts of enteroviral antibodies. Prior to nursing, the serum of new-born pig contained no enteroviral antibodies but, shortly after nursing, high titers of such antibodies were present in the serum. Antibodies were detected in the feces of suckling pigs.