Phostrol fungicide applied early was not effective against root rot of field pea, 2015.
Gossen, B.D., Bassendowski, K.A., Erickson, S., and Chatterton, S. 2016. Phostrol fungicide applied early was not effective against root rot of field pea, 2015. Proc. 18th Intern. Reinhardsbrunn Symposium, April 24 28, 2016, Friedrichroda, Germany. Abstract 64.
Root rot of field pea (Pisum sativum L.), caused by a disease complex that includes Fusarium spp., Pythium spp., and Rhizoctonia solani Kűhn, is becoming an increasing important constraint to pea production on the Canadian prairies. Also, Aphanomyces euteiches Drechs. has recently been shown to be widespread and damaging across the region. No strong sources of root rot resistance are commercially available, and no fungicides have been identified that provide useful reduction in root rot caused by A. euteiches. Phostrol fungicide is one of the few fungicides that is translocated downward to plant roots, and so might protect the crop from root rot. Replicated small-plot field trials were conducted at five sites in 2015; the AAFC research farms at Saskatoon and Melfort, Saskatchewan, and at Lethbridge, Alberta, and two grower fields (one in Saskatchewan, one in Alberta) infested with A. euteiches. The treatments were calcium carbonate participate (4 and 8 T/ha), gypsum (2.2 T/ha), and granular Edge herbicide (13 and 26 kg/ha), broadcast prior to seeding, Phostrol (6 and 12 L/ha) applied ½ at seedling emergence and ½ 14 days later, and a nontreated check. Several treatments increased seedling emergence slightly at Melfort, but others reduced establishment at Saskatoon. There was no effect of treatment at the other three sites, and no positive effect on yield at any site. Spring and early summer conditions across the region in 2015 were drier than normal. As a result, disease pressure from seedling blight and root rot was generally low. Aphanomyces root rot caused substantial injury in the commercial field in Saskatchewan, but none of the treatments had an effect on emergence or yield. These results indicate that no treatment provided effective reduction in root rot severity.