Risk Assessment Latitude Use

Use where take-all is likely

• Second and third wheat
• Winter barley following a cereal
• Earlier drilled crops
• First wheat after set-aside or a spring cereal
• Winter barley, winter or spring wheat

Risk Assessment

Rotation - 33% risk

The two previous crops should be considered. Both have an influence on the level of take-all in the soil.

† Grass: Ploughed-up permanent grassland can have an effect even further back in the rotation, due to the increase in soil organic matter. Risk may be less after a good clean Rye-grass ley because of the action of fungal antagonists (Phialophora spp.)

* Set-aside: Risk is influenced by the time of destruction and cultivation of set-aside. A short interval between destruction and drilling will increase the risk. If set-aside contains mainly cereal volunteers and rhizomatous grasses (e.g. Couch) risk will also be increased.

+ Roots: Risk is increased in second wheat crops if conditions at lifting caused damage to soil structure.

Climatic - 34% risk

Source: Conditions required for take-all development by region 1979-2000. Based on Monsanto FARModel using records of temperature and moisture data.

Soil - 16% risk

Average take-all levels from 415 European field trials with full soil textural analysis.
Note: Soil textural information must be interpreted with great care.

1. Some Silty Clay Loams (e.g. Andover series) are low risk, while others (e.g. Bromyard series) are not. Generally take-all can be severe in wet seasons on soils with high silt content (e.g. Fen or Old Red Sandstone).
2. For Clays and Clay Loams risk is related to chalk content. Well-structured Chalky Boulder Clays (e.g. Hanslope series) are relatively low risk soils, poorly structured Clays (e.g. Ragdale series) restrict rooting and favour infection.
3. Very light soils (e.g. Bunter Sandstone) are high risk - except in very dry seasons.
4. Black Fen (Peat and Loam Peats) are very high risk due to their open puffy nature.

* Take-all can be associated with acid patches.

** On Organic soils (> 6% OM) the relative importance of soil to overall risk is greater.

Source: 133 UK Monsanto field trials mainly from second or third wheat crops. First wheat crops after set-aside or spring barley will be at risk from early to mid September drilling dates.

Other Risk Factors

In addition to the major risk factors above, the following will also increase the risk and likely impact of take-all:

• Variety choice
• Short plough to drilling date
• High seed rates
• Poor weed control in break crops
• Loose seedbeds
• Low Nitrogen
• Nitrate forms of Nitrogen
• Low Phosphate
• Low Potassium
• Manganese deficiency