Take-all is the number one yield robbing disease of UK cereals. Losses are seasonal depending on both weather conditions and the amount of second or subsequent wheats grown. In take-all years individual crop losses vary from 1t/ha up to as much as 50% of the crop, 1979, 1981, 1987, 1998, 2001, 2005 and 2008 were all notably bad years.
The fungus Gaeumannomyces graminis var. tritici infects the roots and the stem base, restricting uptake of water and nutrients. In severe cases, it kills the roots, leading to stunting, chlorosis (leaf bleaching), and whiteheads (ear bleaching).
The fungus is endemic to UK arable soils, and survives on residues from cereal crops. Hosts are wheat, barley, triticale, rye and many grass species such as Common Couch, Ryegrass and Barren Brome.
Take-all is one of the main reasons second and third wheats tend to underperform compared with first wheats.
Early infection with take-all can impact on crop establishment and reduce crop performance. Where left unchecked, yield losses of 1-1.5t/ha are common in second/third wheats. Up to 4t/ha has been lost in severe cases.
Quality is also impaired as specific weight is generally reduced.
Take-all also impacts on flexibility in cropping and drilling date.
In assessing the risk of take-all and its management, it is important to consider the health of the current crop. There are four diseases that make up a stem-base disease complex - true eyespot, sharp eyespot, take-all and Fusarium. They can all cause browning symptoms on the stem/stem base, and whiteheads when infections are severe.
Identifying which is responsible for symptoms is critical to managing disease in the following crop. Follow these steps when preparing roots and stems for examination:
Step 1 - Use a spade to carefully Step 2 - Keep the root mass Step 3 - In light soils
dig up 5 or 6 plants intact tease plants apart by
Step 4 - Soak roots in Step 5 - Carefully rinse loose View on a white background
water for 1 to 12 hours soil from the root system to contrast with take-all
depending on soil type symptoms
Once roots and stems have been cleaned correctly, identification can be made using the Root and Stem Base Disease Guide
Early symptoms of take-all include stunting and chlorosis of foliage and blackening of the roots, seen usually from March onwards depending on severity. Whiteheads tend to occur in patches but are not always apparent.