The structure of Phytophthora infestans populations from organic and conventional crops

Abstract

The characteristics of populations of Phytophthora infestans from organic farms, small conventional farms and large conventional farms were determined from isolates collected in northern Estonia in 2004 and 2005. For the population as a whole 41% were A2; all virulence factors to the 11 R genes from Solanum demissum were found; and more than 70% had high or intermediate resistance to metalaxyl. Isolates from organic farms tended to have more complex pathotypes than isolates from either large or small conventional farms, but there was a higher proportion of metalaxyl resistant isolates from large conventional farms than from small conventional farms or from organic farms.

Highly Diverse Phytophthora infestans Populations Infecting Potato Crops in Pskov Region, North-West Russia

“…Furthermore, the predominance of metalaxyl-sensitive isolates observed in small conventional fields compared to large-scale conventional farming reflects the significant effect of a cultivation system on the selection pressure of a pathogen population, altering the sensitivity levels to active ingredients [ 74 , 89 , 90 , 91 ]. Runno-Paurson et al [ 94 ], recorded a higher proportion of metalaxyl-resistant isolates in large conventional farms compared to small conventional farms, which was also observed in this study. A similar result was also reported by Brylinska et al [ 92 ] and Cooke et al [ 95 ].…”

Diversity of Phytophthora infestans from Poland

“…The Polish population of P. infestans , unlike the French, British or Dutch populations (Montarry et al ., ; Cooke et al ., ; Li et al ., 2012b), remained diversified, with low frequency of the A2 mating type, rare metalaxyl resistance and no single invasive genotypes spreading. It resembled more closely P. infestans populations in the Nordic countries (Denmark, Finland, Norway and Sweden; Brurberg et al ., ) and Estonia (Runno‐Paurson et al ., ), with the majority of isolates of mating type A1 and high genetic variation.…”

“…Domination of Ia mitochondrial haplotype is also common in other European populations of P. infestans , and IIa is widespread, but with a lower frequency. However in Estonia Ia and IIa haplotypes are found in a ratio close to 1:1 (Runno‐Paurson et al ., ).…”

“…In the Czech Republic the majority of P. infestans isolates are sensitive to metalaxyl (95% of isolates collected in 2003Maz akov a et al, 2011). In Estonia 78Á8% of isolates were sensitive to metalaxyl in 2007, although in 2005 only 15Á2% were sensitive (Runno-Paurson et al, 2010). In many other countries high frequencies of isolates resistant to metalaxyl have been reported.…”

Morphological Characterization of Phytophthora infestans and its Growth on Different Growth Media

“…A major concern to get a pure culture of Phytophthora is possible the presence of fast-growing organisms such as Pythium other genera of fungi, which affected the growth of Phytophthora (Canaday and Schmitthenner, 1982). As well, the material of potato seed can affect the fungal co mmunity in the fields (Runno-Paurson et al, 2010b, Drenth et al, 2001Lal et al, 2015). In the present study, morphological characters of sporangial size was undistinguished which was found to be high values of aggressive isolates.…”