Botrytis porri Buchw. on leek as an important storage fungus in Finland

Botrytis porri Buchw. was found to be a common and economically significant pathogenic fungus on leeks in storage. The increase in the number of fungi caused a linear decrease in the number of marketable leeks when stored at 0.5° C. B. porri was found to spoil leeks even at —0.5° C. Spraying with benomyl and thiophanatemethyl one or two weeks before harvesting significantly decreased the numbers of the fungus and the amount of damage caused during storage. Botrytis allii Munn and Fusarium avenaceum Sacc. rarely caused spoilage of leeks.

Colonization and Biochemical Changes in Peanut Seeds Infected with Aspergillus flavus1

Seeds from three commercially grown peanut cultivars and two “resistant” genotypes had varying degrees of resistance to colonization by the storage fungus, Aspergillus flavus. Peanut genotypes PI337409 and PI337394F had significantly higher resistance to colonization than other tested cultivars. Some of the biochemical changes in peanuts resulting from A. flavus infestation included: Reduction of oil and protein content, rapid increase in free fatty acids and changes in the amino acid composition.

Stimulation of fungal spore germination by volatiles from aged seeds

Alaska pea seeds were stored asceptically or with inoculum of Aspergillus ruber, a pathogenic storage fungus, under conditions which induce rapid seed deterioration and permit infection of seeds by A. ruber (30 °C and 92% relative humidity). Volatiles from germinating aged seeds stimulated germination of conidiospores of Fusarium solani f. sp. pisi and Alternaria alternata and chlamydospores of F. solani f. sp. pisi, all in soil-induced stasis, much more than volatiles from unaged seeds. Volatiles from A. ruber - infected seeds were more stimulatory than from comparably aged noninfected seeds when planted in sand, but this effect was not seen when the seeds were planted in soil. Oospores of Pythium ultimum were not stimulated to germinate by volatiles from any seeds. Aged and infected seeds produced up to 24 times more carbonyl compounds than unaged seeds, presumably as a consequence of lipid peroxidation.

Microflora of heat-damaged rapeseed

Microfloral components present on two sound lots (1 and 2) and three sample grade, heat-damaged lots (3 to 5) of stored Canadian rapeseed (Brassica campestris L. and B. napus L.) were determined with and without surface disinfection. Lots 1 and 2 were from a granary and a warehouse, respectively, and lots 3 to 5 were from primary elevators. Seed in lots 4, 5, and 3 showed progressively increased effects of heat damage as shown by the crush test. Sound lots 1 and 2 had mainly Alternaria and Cladosporium spp. with traces of Eurotium amstelodami, E. repens, and Penicillium spp. Lot 4 seed had low–medium levels of Alternaria alternata, Absidia ramosa, E. amstelodami, and Mucor pusillus. Lot 5 had high levels of E. amstelodami and low levels of Talaromyces thermophilus but A. alternata and M. pusillus were largely absent. Lot 3 had deeper-seated E. amstelodami, T. thermophilus, and Penicillium spp. than lots 4 and 5. Eurotium amstelodami was the predominant storage fungus in the heat-damaged lots. During the early stages of heating, E. amstelodami was often accompanied by the primary sugar fungi M. pusillus and A. ramosa, and after severe heating, by T. thermophilus. The thermal death point was between 50 and 60 °C for moist seed and between 80 and 90 °C for dry seed after 30-min exposure. With the exception of E. amstelodami, heat resistance of the fungal flora did not exceed that of the seed.

Physiological changes in the early stages of germination of pea seeds induced by aging and by infection by a storage fungus, Aspergillus ruber

Pea seeds age rapidly and may be infected by storage fungi, e.g. Aspergillus ruber, when stored under conditions of high relative humidity and temperature (92% relative humidity and 30 °C in these experiments). In the absence of microorganisms, pea seeds retain their viability for 6 to 8 weeks, although the speed of germination is reduced. In embryonic axes, aging is associated with a slower increase in O2 uptake, a delay in protein synthesis, smaller ATP and amino acid pools, and reduced activity of alkaline phosphatase (EC 3.1.3.1) and 3-phosphoglyceraldelyde dehydrogenase (EC 1.2.1.12). Axes recover from these changes during germination. Infection by A. ruber reduces germination. In axes from infected peas the onset of protein synthesis is delayed even more and the ATP and amino acid pools are smaller than in aged axes. Axes from infected seeds recover slowly, if at all.