Degradation of diphenamid in soil with accelerated degradation and in nontreated control soil and the involvement of soil microorganisms in these processes were investigated. Soil with accelerated degradation and mixed bacterial cultures originating from the same soil degraded diphenamid and its monodemethylated metabolite (diphen M-1) much faster than the control. The bidemethylated derivative (diphen M-2) was degraded much more slowly than diphenamid or diphen M-1. The abundance of fungi capable of degrading diphenamid was similar in the soils with and without accelerated degradation. Degradation of diphenamid by mixed bacterial cultures from a soil with accelerated degradation was much faster than by a culture from nontreated soil and was suppressed by the fungicides thiram and fentin acetate. These two fungicides, as well as the bactericide chloramphenicol, suppressed diphenamid degradation in mixed bacterial cultures. The antifungal cycloheximide and the actinomycete suppressor PCNB did not affect the degradation of diphenamid. Metabolism of 14C-diphenamid in a soil with accelerated degradation and in mixed bacterial cultures originating from the same soil showed similarities with regard to evolution of 14CO2 and production of certain metabolites, while the metabolism of diphenamid by Fusarium, which rapidly degrades diphenamid in cultures, was different with regard to the above parameters. This study suggests that development of accelerated degradation in a soil involves a shift in population and/or in activity of microbial degraders in favor of bacteria. It appears that the accelerated degradation occurred by inducing oxidative reaction which involves demethylation of diphenamid.

An accurate method is described for evaluating the relative effectiveness of isolates of Fusarium avenaceum as potential biological control agents for weeds such as spotted knapweed and wild oat. The method uses seeds that have been disinfected, placed in tubes containing water agar, and challenged with various isolates of F. avenaceum. Evaluatory data on the pathogenicity of the fungi are obtained after 14 d, when plants and fungi both are grown on water agar in the lab. Commonly, potential biocontrol agents are tested on seeds placed in the soil, but up to 60 d may be required for results. However, comparative studies using the soil test vs. the water agar test indicated that the water agar tests are giving comparable results to those from greenhouse tests but in a shorter time (14 vs. 60 d). Also, both water agar and soil tests were done with a number of crop plants including wheat, barley, alfalfa, and wild oat with comparable results. Thus, this method has the potential to screen many pathogens that may have potential biocontrol activities in a short time.

Experiments were set up to assess the relative impacts of grass lamina fragment density, size and quality on the activity and growth of four fungi in a particulate soil-like matrix. The fungi studied were Cladosporium cladosporioides, Fusarium lateritium, Phoma exigua and Trichoderma viride, all of which are common inhabitants of UK upland grassland soils. Resource quality was varied by using three contrasting grasses as sources of lamina fragments: Lolium perenne, Agrostis capillaris and Nardus stricta. All the fungi were able to forage effectively through the soil-like matrix (at a rate of 1–2 ml matrix d−1) and colonize and partially decompose available lamina fragments (up to 40% d. wt loss). Foraging rates (ml matrix d−1) were affected by lamina fragment species but not by fragment density or size. In general, F. lateritium and T. viride foraged at a faster rate than the other species. Mycelial activity in the soil-like matrix was directly proportional to total lamina fragment availability and was unaffected by fragment size. Biomass production on solid media was also directly related to substrate (carbohydrate) availability. The results indicate that these fungi can adjust their growth patterns in response to fragment density so as to maximize foraging efficiency (energy acquired per unit exploratory biomass production). Differences in lamina fragment species were responsible for up to 50% reduction in mycelial activity.

Six genera of bacteria: Serratia, Providencia, Enterobacter, Aeromonas, Cedecea and Bacillus were isolated from field-collected G. pallidipes. Four genera: Serratia, Providencia, Enterobacter and Aeromonas were isolated from insectary-reared Glossina morsitans morsitans. All bacteria except, Bacillus spp. and Providencia alcalifaciens were pathogenic for teneral G. m. morsitans. Bacteria isolated from insectary-reared tsetse were more pathogenic than those isolated from the field. Fungi of three genera were also isolated from field-collected adult G. pallidipes, Penicillium, Aspergillus and Fusarium. Five genera, Aspergillus, Penicillium, Rhizopus, Mucor and Trichoderma were isolated from field-collected G. pallidipes pupae. The fungi, however, were only mildly pathogenic for adult tsetse and were not pathogenic for pupae.

A method for steady production of Chilo partellus has been established. An efficient simple and easy method of collection of first instar larvae from incubation chambers has been developed. It has been established that pupae of Chilo partellus can be held at a chilling temperature between 5 and 15°C without any adverse effect on the emergence of adults. This finding has been used in synchronizing the emergence of males and females for mating or longer storage of the pupae.

Studies on the effect of high and low humidities on egg development have shown that low humidities affect the hatchability of Chilo partellus egg but did not effect the actual development of the embryo adversely. It has also been shown that Chilo partellus oviposits best under high humidity.