Three metalaxyl sensitivity levels in Australian isolates of Pseudoperonospora cubensis (Berk. et Curt.) Rost

O'Brien, R. G.; Weinert, M. P.

doi:10.1071/ea9950543

Cited by 6 publications

(1 citation statement)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Phytophthora species are generally sensitive to 0·01 to 1 mg L −1 of metalaxyl‐M (Erwin & Ribeiro, 1996). EC 50 values of natural MR isolates (not laboratory‐induced) of species in the order Peronosporales are commonly over 100 times more resistant than those of MS isolates (White et al ., 1988; Ferrin & Kabashima, 1991; Klein, 1994; O’Brien & Weinert, 1995; Pankhurst et al ., 1995; Sujkowski et al ., 1995; Timmer et al ., 1998), and EC 50 values of MR isolates of P. erythroseptica from Idaho in the present study were on average 380 times more resistant than MS isolates.…”

Section: Discussionmentioning

confidence: 99%

In vitro somatic growth and reproduction of phenylamide‐resistant and ‐sensitive isolates of Phytophthora erythroseptica from infected potato tubers in Idaho

Porter¹,

Miller

Nolte

et al. 2006

Plant Pathology

View full text Add to dashboard Cite

Pink rot of potato, most commonly caused by Phytophthora erythroseptica , is a major field and post-harvest problem in southern Idaho, USA, particularly since 1998 when isolates resistant to the phenylamide fungicide metalaxyl-M (mefenoxam) were detected. Isolates of P. erythroseptica were collected from infected tubers in 2001 and 2002 from six Idaho counties and tested for resistance to metalaxyl-M on amended agar. Metalaxyl-M resistant (MR) and metalaxyl-M-sensitive (MS) isolates were identified in six counties; 160 isolates were highly resistant, seven moderately resistant and 57 sensitive to metalaxyl-M with mean EC 50 values of 182, 23 and 0·5 mg L − 1 ai metalaxyl-M, respectively. Mycelial growth rates and oospore production in agar were assessed for 20 MS and 20 MR isolates at 10, 15, 20, 25 and 30 ° C. Growth rates of MR isolates were between 2·5 and 3·1 times greater ( P < 0·05) than those of MS isolates at 10, 15, 20 and 25 ° C, and oospore production was between 6·8 and 20·5 times greater ( P < 0·0001) for MR than for MS isolates at the same temperatures. Colony growth in V8 broth at 18 ° C was greater for MR than MS isolates ( P < 0·0032). However, zoospore production at 18 ° C was greater for MS than for MR isolates ( P < 0·0109), and zoospore production m m − 1 of colony circumference was also greater for MS than for MR isolates, 14 191 and 9959, respectively ( P = 0·0109).Sexual reproduction of MR isolates in nature may be greater than MS isolates, but MS isolates may be more asexually fit based on the fitness parameters studied.

show abstract