KWS

Rhizoctonia

Rhizoctonia solani is †a world-wide fungus which is present in almost all soils.

  • Depending on the affiliation to an anastomosis group Rhizoctonia solani† can attack different crops; the AG 2-2 causes Late Root Rot on sugar beet.
  • The fungus survives in the form of sclerotia, as mycelium and/or on organic matter in the soil.
  • Warm climates and high soil moisture favour attack by Rhizoctonia solani.
  • The infection manifests itself from summer to autumn firstly in small patches. The beets wilt and show poor growth.
  • Greyish-brown to black rotten patches and fissures appear on the root body, in the case of welladvanced root rot the wilted leaves lie starlike around the beet on the ground.
  • There are possibilities of confusion with various pathogens attacking the root body. Reliable diagnosis of Late Root Rot can only be made by laboratory analysis.
  • With good husbandry measures (including crop rotation, intercropping, avoidance of damage to the soil structure by timely use of machinery, correct nutrient application) the damage can be reduced.
  • On severely infected areas the choice of varieties is of vital importance. Registered varieties with tolerance to Rhizoctonia solani are available.

Rhizoctonia solani as pathogen of Late Root Rot has gained in importance in European beet growing areas within the last decade. With substantial farming and plant cultivation techniques the grower can assist a reduction in damage; these are an extension of crop rotation, the improvement of soil structure by timely cultivations and catch crop growing as well as the choice of varieties.

Varieties have already been registered in various countries which prove that KWS has rapidly reacted to the farmers' demands. In addition, current work in the seed technology field focus on the control of Rhizoctonia solani by means of seed treatment with special fungicides and/or antagonists, in order to prevent an early infection with the disease. Meanwhile, high-performing varieties are available with a combined resistance to Rhizoctonia

and Rhizomania. Thus, KWS makes a substantial contribution to an environmentally beneficial growing method in favour of a sustainable agriculture.

Root Rots found in many sugar beet clamps in the UK have a number of origins. They can originate from the field from infections on roots suffering mechanical, pest or drought damage, or poor soil structure. However, in addition to good cultural husbandry in the field, attention should also be paid to constructing a free draining, well ventilated clamp.


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