Rhizoctonia solaniinjuries in oilseed crops in Finland and impacts of different crop management practices on disease incidence and severity

Abstract

A disease survey in Finnish oilseed Brassica (OSR) fields in 2007-09 revealed the widespread occurrence and several fold increase of necrotic stem base lesions and severely injured blackened roots in comparison to a corresponding survey carried out in 1984-89. Rhizoctonia solani was the predominant fungi detected in the isolations and was followed by several species of Fusarium and Thielaviopsis basicola. In 60% of the samples all three species were detected together. Only the R. solani AG 2-1 strains isolated from OSR and other cruciferous hosts caused damping off or stem base symptoms on turnip rape in a greenhouse experiment. Therefore R. solani AG 2-1 was considered the main pathogen associated with the observed symptoms in OSR crops. Cultural practices changed significantly between the 1980s and 2000s. In the 2007-09 survey there was an increase in the cultivation of oilseed rape instead of turnip rape, increase in the use of no soil or reduced soil tillage and of chemical control of weeds, but a reduction in macronutrient fertilization, especially P and K, when compared to the 1980s survey. The risk for high incidence of stem base lesions and blackened roots was affected by different cultural practices. No tillage and maintaining sufficient soil pH and NPK fertilisation decreased the risk for both types of R. solani induced symptoms. Late sowing date increased the risk for high incidence of stem base lesions, while application of fungicides against Sclerotinia reduced it. The incidence of R. solani damages in many fields was very high in spite of relatively long crop rotations and therefore the average effect of crop rotation in the disease was insignificant. Current turnip rape cultivars are vulnerable to root rot while oilseed rape is vulnerable to stem base symptoms. The higher incidence of R. solani induced diseases could be associated with the decline in productivity of OSR crops in Finland. This study showed that cultural practices such as reduced or no soil tillage, adequate levels of pH and of NPK fertilization could reduce the severity of the symptoms in OSR fields.

Fungal community profiles in agricultural soils of a long-term field trial under different tillage, fertilization and crop rotation conditions analyzed by high-throughput ITS-amplicon sequencing

“…solani and T . basicola was found in the variants with reduced tillage and fertilization [ 50 ], which may be due to different geo-climatic conditions.…”

Interactive tool for farmers to diversify high-latitude cereal-dominated crop rotations

“…The shares of all remaining crops increased, but especially rapeseed gained more parcels as did peas, winter rye and spring wheat (Table 2). The tool acknowledges the need for a lagperiod for cultivation, depending on the crop, to avoid increases in their crop protection risks (Hannukkala et al, 2016;Huusela-Veistola & Jauhiainen, 2006).…”

Evaluation of the Effect of Different Sowing Dates and Cultivars against Canola Root Rot Diseases

“…Kesimci et al (2016) found that the sowing date significantly influenced the root-rot and wilt diseases of faba bean cultivars. Hannukkala et al (2016) found that late sowing date increased the risk for high incidence of stem base lesions in oil seed crops.…”