Effects of carbathiin and thiram with propiconazole and aldicarb on grain yield, and on incidence of root rot, leaf blotch, and root lesion nematode in spring wheat

• Published in: Canadian journal of plant pathology 1998-06, Vol.20 (2), p.201-205
• Main Authors: Kimpinski, J, Johnston, H.W, Sanderson, J.B
• Format: Article
• Language: English
• Subjects: aldicarb; application rate; blight; Cochliobolus sativus; crop yield; fungicides; fungus control; incidence; Leptosphaeria; population; population density; Pratylenchus penetrans; propiconazole; rhizosphere; root rot; roots; seed weight; thiram; Triticum aestivum
• ISSN: 0706-0661; 1715-2992
• DOI: 10.1080/07060669809500428

Grain yields of spring wheat (Triticum aestivum cv. Belvedere) in experimental plots were increased by an average of 50% over three years when carbathiin and thiram were applied at 0.55 g a.i. kg(-1) of seed to control seedling disease, propiconazole was applied at 125 g a.i. ha(-1) to control leaf diseases, and aldicarb was broadcast and incorporated into soil at 2.24 kg a.i. ha(-1) to suppress nematodes. The 3-y average hectolitre wt and 1000-kernel dry wt were also increased by the treatments. The analyses of variance indicated that the effects of the fungicides and aldicarb treatments were additive and not interacting. The analyses of covariance showed that the significant treatment effects on grain yield and hectolitre wt were reduced to insignificance when the variables nematodes g(-1) of total root and kg(-1) of soil obtained 1 day before harvest were used as covariates. The 3-y average incidence of common root rot, incited by Cochliobolus sativus, was not suppressed by the fungicide treatments. Based on 3-y averages, root rot ratings increased from 30.4% at Zadoks Growth Stage (ZGS) 30-32 in July to 49.7% at ZGS 70-72 in the first half of September. Leaf disease, incited primarily by Stagonospora nodorum was reduced by the fungicide treatments. Aldicarb reduced the population levels of the root lesion nematode Pratylenchus penetrans in soil, in the total root system, and in seminal and crown roots. The population densities of root lesion nematodes were about five times higher in seminal roots than in crown roots. There were two significant (P less than or equal to 0.05) positive correlations between fungal and nematode data in 1988: the incidence of leaf disease obtained in late July, and the average incidence of root rot obtained at ZGS 30-32, 55-60, and 70-72 were correlated with the number of nematodes in the total root system in late September. There were no other significant relationships (P < 0.05) between the incidences of root rot or foliar disease and numbers of root lesion nematodes in soil or roots. We conclude that root lesion nematodes, as well as fungal pathogens, cause significant yield losses in spring wheat in eastern Canada.