Soil with the spores of fungi in dormant stage from previous years infections belonging to the genus Fusarium caused significant loss of onion yield in Poland. The most important form of Fusarium inoculum in the field are chlamydospores, which may survive in soil for many years. There are no available methods to eradicate chlamydospores from soil environment. Inspired by data from the literature and own prelimi–nary observation, we evaluated the effect of application of Brassicaceae plant material to the soil infested with F. oxysporum and F. solani isolates, which are pathogenic to onion. Obtained results showed that addition of fresh plant material from B. juncea and B. alba had no effect on amount of Fusarium propagules in the soil. Moreover amendment of infested soil with dry plants or milled seeds of B. juncea or B. nigra significantly stimulated the population of Fusarium in the soil.
Urszula Smolińska, Beata Kowalska, Waldemar Kowalczyk, Magdalena Szczech and Aleksandra Murgrabia
Sclerotinia sclerotiorum (Lib.) de Bary is considered as one of the most harmful soilborne pathogens, which reduces productivity of horticultural crops. Currently used chemical or biological methods for the eradication of S. sclerotiorum from a soil are not very effective. The aim of this study was to evaluate the possibility of eradication of S. sclerotiorum sclerotia from a soil using the Trichoderma isolates, which were multiplied on the organic carriers prepared from agro-industrial wastes and by-products: WsA (wheat straw + apple pomaces), WsP (wheat straw + potato pulp) and T-GRAN (dry onion rind, apples and strawberry pomaces, rapeseed meal). The results showed that soil amendment with organic materials overgrown with the Trichoderma fungi had a significant reducing effect on S. sclerotiorum. Especially effective was the carrier WsA overgrown with T. virens TRS114, which completely prevented the survival of sclerotia of S. sclerotiorum regardless of the dose of application. Less effective was the WsP carrier. However, addition WsP overgrown with T. atroviride TRS40 at the 5% w/v, resulted in survival only 6.7% of sclerotia. In the greenhouse experiments with lettuce, the application of granulates T-GRAN into the soil had different impact on S. sclerotiorum depending on the conditions to the pathogen development. In conducive conditions, an addition of the organic substances without Trichoderma significantly decreased the yield of lettuce plants. A positive effect on the growth of plants was observed after the application of T-GRAN overgrown with Trichoderma.
Magdalena Szczech, Anna Szafirowska, Waldemar Kowalczyk, Justyna Szwejda-Grzybowska, Agnieszka Włodarek and Robert Maciorowski
Application of beneficial bacterial strain B125 (Enterobacter sp.) and strain PZ9 (Bacillus sp.) in lettuce transplants production significantly enhanced seed germination and plant biomass. The best effect was obtained when the mixture of B125 and PZ9 was used. Combined application of these bacteria significantly increased transplants biomass, which was about 45% higher than that in the control. However, after planting these transplants in organic field, generally, there were no differences in yield and nutrient content in plants treated and not treated with the bacteria, except for nitrogen and vitamin C. The lettuce grown from transplants treated with bacterial mixture B125 + PZ9 contained significantly higher nitrogen than plants from other treatments. Opposite to nitrogen, bacterial applications decreased the amount of vitamin C. The growth and organic lettuce composition was affected by planting time. The yield was higher in spring, but the concentration of nutrients in these plants was lower than that in plants harvested in autumn. Climatic and light conditions in the late season were the reasons for increased dry matter content, minerals, phenolic compounds, and vitamin C, as well as high concentration of nitrates.