Assessment of recent outbreaks of Dickeya sp (syn. Erwinia chrysanthemi) slow wilt in potato crops in Israel

Suspected Dickeya sp. strains were obtained from potato plants and tubers collected from commercial plots. The disease was observed on crops of various cultivars grown from seed tubers imported from the Netherlands during the spring seasons of 2004-2006, with disease incidence of 2-30% ( 10% in average). In addition to typical wilting symptoms on the foliage, in cases of severe infection, progeny tubers were rotten in the soil. Six strains were characterised by biochemical, serological and PCR amplification. All tests verified the strains as Dickeya sp. The repPCR and the biochemical assays showed that the strains isolated from blackleg diseased plants in Israel were very similar, if not identical to strains isolated from Dutch seed potatoes, suggesting that the infection in Israel originated from the Dutch seed. The strains were distantly related to D. dianthicola strains, typically found in potatoes in Western Europe, and were similar to biovar 3 D. dadanti or D. zeae. This is the first time that the presence of biovar 3 strains in potato in the Netherlands is described. One of the strains was used for pathogenicity assays on potato cvs Nicola and Mondial. Symptoms appeared 2 to 3 days after stem inoculation, and 7 to 10 days after soil inoculation. The control plants treated with water, or plants inoculated with Pectobacterium carotovorum, did not develop any symptoms with either method of inoculation. The identity of Dickeya sp. and P. carotovorum re- isolated from inoculated plants was confirmed by PCR and ELISA

PREPARATION PROCEDURES OF FUNGAL PHYTO-PATHOGENS SAMPLES FOR ANALYSIS BY MALDI-TOF AND FTIR MICROSCOPY

Reliable and rapid identification of phyto-pathogens causing plant diseases is playing an important role in their control strategies. The available methods for identification of fungi are time consuming and not always very specific. MALDI-TOF and Fourier-transform infrared (FTIR) microscopy are proved to be comprehensive and sensitive analytical methods for detection of molecular changes in cells. Due to the similarity between the obtained spectra of different species of fungal pathogens, it is important to choose the most appropriate procedure for the preparation of the examined samples. Such procedure might improve the discrimination between these species. In the present study, we compared between three possible procedures of pathogen sample preparation for their examination by MALDI-TOF and FTIR microscopy. Our results showed that preparation of the fungal sample directly from liquid growth media is considered as the best way of fungal sample preparation for both MALDI-TOF and FTIR microscopy examination

Environment-friendly agent [SG101] for the Control of Common Scab on Potato

Common scab on potato, caused by Streptomyces spp., can result in severe damage to pota-toes. The increased prevalence of this disease in Israel, especially in Ma'on region (South-West Israel), is attributable to several factors, among which are: susceptible crops such as peanuts and radish being grown in short rotations, soils that are conducive to the disease, and the absence of effective eradication methods. Contaminated potato seed tubers are the major means of spreading the pathogen. Seed borne inoculum arrives through certified seed lots imported from Northern-Europe for the spring. In average 26% of the seed lots were contaminated with intermediate and high levels of common scab between 2004 and 2007.However, so far any of the tested seed treatments was efficient in reducing the disease incidence or severity. The primary inoculum source of Sreptomyces is seed tubers. Once the pathogen is introduced and established into the soil, it survives for a long time, and only a radical soil fumigation (such as formaldehyde) can reduce the pathogen levels. The objective of the present study was to evaluate SG101, a stabilized formulation of hy-drogen peroxide agent (3.5-7% H2O2) as a seed treatment for controlling common scab on potatoes. Seed tubers (cv. Desiree) highly contaminated with common scab were treated with SG101 or Bactoril (Quat Ammonium) by a low volume spray, and mancozeb by dusting. Two experiments arranged in a randomized complete block design, with four replications were planted in two sites (Gilat -loess soil and Halutza - sandy soil). In Gilat, the incidence of progeny tubers with russet scab was significantly reduced in both SG101 and mancozeb treatments. In Halutza, the incidence of russet and common scab were significantly lowerin SG101, compared with the control and Bactoril. mancozeb treatment.The findings in this study indicate the high potential of using SG101 as a seed treatment for controlling scab in the short-term (in the harvested progeny). Furthermore, because of this SG101 efficiency, an advantage for the long-term is being achieved, by preventing the spread of the pathogen and infestation of soils. Additional studies on the potential use of SG101 as a furrow treatment and its effect on other seed-borne pathogens are being currently conducted.vokMyynti MTT Tietopalvelut 31600 Jokioine

Assessment of recent outbreaks of Dickeya sp (syn. Erwinia chrysanthemi) slow wilt in potato crops in Israel

Suspected Dickeya sp. strains were obtained from potato plants and tubers collected from commercial plots. The disease was observed on crops of various cultivars grown from seed tubers imported from the Netherlands during the spring seasons of 2004-2006, with disease incidence of 2-30% ( 10% in average). In addition to typical wilting symptoms on the foliage, in cases of severe infection, progeny tubers were rotten in the soil. Six strains were characterised by biochemical, serological and PCR amplification. All tests verified the strains as Dickeya sp. The repPCR and the biochemical assays showed that the strains isolated from blackleg diseased plants in Israel were very similar, if not identical to strains isolated from Dutch seed potatoes, suggesting that the infection in Israel originated from the Dutch seed. The strains were distantly related to D. dianthicola strains, typically found in potatoes in Western Europe, and were similar to biovar 3 D. dadanti or D. zeae. This is the first time that the presence of biovar 3 strains in potato in the Netherlands is described. One of the strains was used for pathogenicity assays on potato cvs Nicola and Mondial. Symptoms appeared 2 to 3 days after stem inoculation, and 7 to 10 days after soil inoculation. The control plants treated with water, or plants inoculated with Pectobacterium carotovorum, did not develop any symptoms with either method of inoculation. The identity of Dickeya sp. and P. carotovorum re- isolated from inoculated plants was confirmed by PCR and ELISA