Harvesting Benefits

Once the crop reaches 30% moisture the application of low rates of Roundup can give harvesting benefits in the absence of weeds. It can facilitate a more timely harvest, achieve maximum combine efficiency, and allow better planning of farm workload.

By reducing moisture and evening up ripening it allows for:

  • Faster combining
  • Fewer green grains
  • Lower drying costs
  • Reduced separation losses
  • Lower admixture
  • In wheat it also gives protection of Hagberg Falling Number

At harvest even though cereal ears can show moisture levels of 16% the leaves and stems will have a much higher moisture level. During combining moisture will be transferred to the grain by condensation. Often grain moisture can rise to 19-20%. Roundup can reduce this effect.

Efficient combining means sustaining maximum output and requires a clean standing crop evenly ripened to a moisture content of 16-18%. The use of Roundup pre-harvest allows higher combine speeds while still maintaining low grain losses.

Treated straw should not be used as horticultural growth medium or mulch, but can be safely used as animal bedding.


Mycotoxins are toxic chemicals produced by naturally occurring moulds and some plant pathogens. Concern about the presence of mycotoxins in European-produced grain led to the EU introduction of threshold levels for some mycotoxins. The British Food Standards Agency introduced EU standards of 1.250 ppm DON in unprocessed wheat grain and 0.75 ppm in grain and flour products in 2006.

Crop Infections

Fusarium ear blight, (F.culmorum & F.graminearum), produces two of the most prevalent mycotoxins – nivalenol and deoxynivalenol, (DON). F.culomorum is the main cause of DON in the UK. Wheat crops following maize are most at risk, hence the problem is far worse in other parts of Europe and North America where maize is more often included in rotations and levels of F.graminearum are much higher. UK producers should be able to achieve EU standards with good fungicide management and timely harvesting, but a Harper Adams/HGCA 5 year study still found 3.5% of grain samples exceeded the DON limit.

The Food Standards Agency Code of Practice to reduce fusarium mycotoxins in Cereals, 2007, states: 'Grain should be harvested as soon as possible once ripe. The concentration of fusarium mycotoxins can increase if harvest is delayed due to wet weather. It is important that preparations are made for harvest to ensure delays are minimised'.

Wet conditions at flowering encourage development of fusarium, so T3 fungicide choices should be made according to risk. Discuss T3 fungicide options with your agronomist.

Stored Grain Infections

Storage mycotoxins such as Ochratoxin A, (OA), produced by Penicillin spp. do not develop if the grain is consistently below 17% moisture, but infections can take hold within days if moisture levels are 20% or above.

Wet harvests have produced samples of grain in the UK with levels exceeding the proposed EU limit of 0.005ppm.

The Use of Roundup

Use of Roundup can produce drier grain, and therefore reduce the time taken to dry down to the critical 17% moisture level. This can reduce the chances of hot spots of infection building up in store.

If difficult, wet harvesting conditions are followed by continuing warm, moist autumn conditions, the time taken to dry down is prolonged. Harvest Management can help minimise this risk.

Crops Cereals, includes winter and spring wheat, (including durum wheat), winter and spring barley, winter and spring oats When used as directed, Roundup treatment is approved on crops intended for feed, milling, malting and distilling. Consult your grain merchant before treating any crop intended for malting or distilling or grown on contract A statutory harvest interval of 7 days should be allowed before combining.

Foraged whole-crop cereals and crimping

Whole-crop silage
Cereals to be cut for whole-crop silage can be treated under the grass silage approvals as grass. A 5 day cutting interval is required.
Wheat, barley or other cereals to be combined for grain must be treated at less than 30 % moisture .This means crimping of crops combined at over 35% grain moisture falls outside Roundup approvals and is not recommended.
This technique uses mostly feed wheats, but can also be used with barley, naked oats or Triticale. The whole crop is harvested using a modified forage harvester and is clamped using an alkaline preservative. This relies on the release of Ammonia gas for a dry preservation, not fermented into acidic silage as conventional silage. The resulting feed is 60% plus dry matter, high energy feed which compliments acidic grass silage and is said to lead to increased milk yields and reduced fertility and lameness problems. The technique is finding favour with dairy farmers as it is home grown, fully traceable and has a wide harvest window. The timing for cutting starts around 35% grain moisture and can be as late as 25% grain moisture. Where crops are full of weeds and 30% moisture or below Roundup treatments can be used under the cereals recommendation. However, because the crop is whole-crop foraged and clamped it can still be used under the grass silage recommendations during the earlier part of the harvesting time. By removing sappy weeds, with the use of Roundup, good Alkalage can be made from weedy crops, which would otherwise have had too low a dry matter %.