Genetic Differentiation of Populations Recovered from Symptomatic and Asymptomatic Hosts.

is a soilborne fungal pathogen affecting many economically important crops that can also infect weeds and rotational crops with no apparent disease symptoms. The main research goal was to test the hypothesis that populations recovered from asymptomatic rotational crops and weed species are evolutionarily and genetically distinct from symptomatic hosts. We collected isolates from symptomatic and asymptomatic hosts growing in fields with histories of Verticillium wilt of potato in Israel and Pennsylvania (United States), and used genotyping-by-sequencing to analyze the evolutionary history and genetic differentiation between populations of different hosts.

Management of Verticillium Wilt of Avocado Using Tolerant Rootstocks.

The global avocado industry is growing, and farmers are seeking to expand their plantations. However, many lands suitable for avocado planting were previously cultivated with hosts of the soil-borne fungal pathogen , which is the causal agent of Verticillium wilt (VW). VW can seriously impair avocado orchards, and therefore, planting on infested soil is not recommended.

Pectate lyase affects pathogenicity in natural isolates of Colletotrichum coccodes and in pelA gene-disrupted and gene-overexpressing mutant lines.

Colletotrichum coccodes (Wallr.) S. Hughes, the causal agent of black dot on potato and anthracnose on tomato, reduces yield and crop quality.

Postharvest dark skin spots in potato tubers are an oversuberization response to Rhizoctonia solani infection.

Israeli farmers export 250,000 tons of potato tubers annually, ≈40,000 tons of which are harvested early, before skin set. In recent years, there has been an increase in the occurrence of dark skin spots on early-harvested potato tubers ('Nicola') packed in large bags containing peat to retain moisture. The irregular necrotic spots form during storage and overseas transport.

Dickeya species relatedness and clade structure determined by comparison of recA sequences.

Using sequences from the recA locus, we have produced a phylogeny of 188 Dickeya strains from culture collections and identified species relatedness and subspecies clade structure within the genus. Of the six recognized species, Dickeya paradisiaca, D. chrysanthemi and D.

Discrimination of soil-borne fungi using fourier transform infrared attenuated total reflection spectroscopy.

Fourier transform infrared (FT-IR) attenuated total reflection (ATR) spectroscopy was used to discriminate five commonly encountered soil-borne fungi that cause severe economic damage to agriculture: Colletotrichum, Fusarium, Pythium, Rhizoctonia, and Verticillium. Contrary to previous studies related to microorganism discrimination using FT-IR-ATR spectroscopy, the pathogen samples were not dried on the ATR crystal, which is a time-consuming operation. Rather, after removing some pathogen filaments from the solution using tweezers, these were placed directly on a flat ATR crystal and pressure was applied using a pressure clamp.

Early and rapid detection of potato's fungal infection by Fourier transform infrared microscopy.

Fungi are considered serious pathogens to many plants and can cause severe economic damage. Early detection of these pathogens is very important and might be critical for their control. The available methods for detection of fungi are time consuming and not always very specific.

Effect of Colletotrichum coccodes on Potato Yield, Tuber Quality, and Stem Colonization During Spring and Autumn.

The response of five potato cultivars to Colletotrichum coccodes was tested in artificially inoculated fields for three consecutive spring and autumn seasons during 1994 to 1996. Significant yield reductions (22 to 30%) were observed in all tested cultivars. Results varied between years, but yield losses were more severe in autumn than in spring.

Verticillium Wilt of Paprika Caused by a Highly Virulent Isolate of Verticillium dahliae.

Verticillium dahliae caused wilting, stunting and early dying of paprika plants in Israel, resulting in a 22% reduction in yield. A V. dahliae isolate from diseased paprika plants was slower growing on agar medium than V.