Effects of cultivation on Rhizoctonia root rot, cereal cyst nematode, common root rot and yield of wheat in the Victorian Mallee

Abstract

The effects of method, time and number of cultivations on root diseases and yield of wheat were studied in a field experiment, in 1985, on a calcareous sandy loam in the Victorian Mallee. The incidence and severity of rhizoctonia root rot (Rhizoctonia solani) were higher in direct-drilled wheat than in wheat sown after cultivation. Compared with direct drilling, the severity of rhizoctonia root rot in seedlings was reduced by 40% with cultivation 20 weeks before sowing; by 70% with cultivation 1 day before sowing; and by 90% with 2 cultivations, the first at 16 weeks and the second 1 day before sowing. Cultivation generally increased the incidence of common root rot (Bipolaris sorokiniana) but had no significant effects on the severity of damage by the cereal cyst nematode (Heterodera avenae) or the number of nematode cysts produced, compared with direct drilling. The incidence and severity of root diseases, and the number of H. avenae cysts produced, were not significantly different in wheat sown after rotary hoeing than in wheat sown after scarifying. The severity of damage by H. avenae, the number of nematode cysts and the incidence of common root rot were higher (45, 70 and 36%, respectively) when scarifying was done 1 day before sowing, compared with scarifying 20 weeks earlier. Differences in sowing depth probably caused this effect since seed was sown deeper (as indicated by subcrown internode lengths) and plant emergence was less in the latter treatment. The timing and number of cultivations with a rotary hoe, however, did not significantly affect the severity of damage by H. avenae, the number of nematode cysts or the incidence of common root rot. The incidence of common root rot was correlated (r = 0.71) with the subcrown internode lengths, indicating that the deeper the seed was sown the greater the proportion of plants with the disease. Dry weight of seedlings and grain yield were negatively correlated (r = -0.79 and -0.66) with the severity of damage caused by H. avenae. Plant dry weight and grain yield were, however, not correlated with the severity of rhizoctonia root rot or the incidence of common root rot.

Current Status of Cereal Root Diseases in Western Australia Under Intensive Cereal Production and Their Comparison with the Historical Survey Conducted During 1976–1982

“…Unlike other root diseases, this disease is not affected by cultivation, and its incidence is correlated with deep sown seed (De Boer et al. ).…”

Fungi Associated with Foot Rots on Winter Wheat in Northwest Italy

“…D, sorokiniattit and F. avenacettm were present during all the considered growing period of wheat plants. D. sorokiniatia has been reported as the dotninant pathogen in the cotnplex of root rot fungi in several countries (Jalaluddin and Anwar, 1989;Loban, 1990;De Boer et al, 1991), but it has been rarely reported in Europe (Marin, 1986;Frisullo and Rossi, 1991).…”

Interaction between zinc nutritional status of cereals and Rhizoctonia root rot severity

“…Minimum tillage in the form of direct-drilling is recommended and increasingly is being adopted, but it has been associated with an increased incidence of bare patch (de Boer et al, 1991). This practice can increase the risk of soil erosion in the wheat growing areas of southern Australia where the surface soil texture is sandy.…”

“…The disease is also a problem in other parts of the world, such as England (Dillon-Weston and Garrett, 1943), Canada (Benedict and Mountain, 1956), the Pacific Northwest of the USA (Weller et al, 1986) and South Africa (Scott et al, 1979). At present, the only effective way to control this disease is by two or more tillage operations before sowing (de Boer et al, 1991) because other control strategies such as fungicide (Smiley et al, 1990), breeding for resistance (Purss and Dub6, 1984) and alternative cropping systems (Rovira, 1986) are still unsuccessful. Multiple cultivations using wide tynes causes significant soil disturbance, disrupting the network of fungal hyphae in the surface soil (Rovira, 1986).…”