West: Rains bring flush of broad-leaved weeds

Mid May approaches and once again we are seeing the characteristic leveling out of growth stages across a range of crops.

Earliest wheats are now at GS 38 (flag leaf half emerged) while all winter barley irrespective of sowing date has awns emerged. Six row hybrids are now well into ear emergence. Oil seed rape is slowly reverting from yellow to green.

Recent rains have benefited crops, however, the down side has been a late flush of broad-leaved weeds, especially fat hen, redshank and bindweed. We may apply an herbicide between T1 and T2 on some crops to take out these weeds while they are small.

The cost of weed control in winter cereal crops, particularly when you factor in blackgrass, is becoming penal. Talking of weeds now is a good time to start mapping patches of grassweeds, having a long hard think why they were not controlled and considering resistance testing if no obvious answer can be thought of.

Spring cropping remains an option although you must consider the range of control that is obtained. Spring crops have to be established well into a clean seed-bed otherwise there can still be a substantial seed return.

Disease wise septoria remains the main threat in winter wheat. We are seeing a large demarcation between varieties. A Recommended List rating of 6 appears to be the tipping point. At this or above infection remains at leaf 5 or below while less resistant varieties have disease showing on leaf 4. We believe fungicide programmes have been robust enough to keep the top three leaves clean.

A salutary thought is that what we are now spending on a T1 would have been an expensive T2 15 years ago. It almost goes without saying that the all-important flag leaf spray will be based on a strong SDHI with curative activity.

“To CTL (chlorothalonil) or not CTL, that is the question” We will use a straight bixafen/prothioconazole based material on cleaner varieties such as Crusoe and opt for fluxopyroxad/epoxiconazole plus chlorothalonil on varieties with a higher rust risk such as Kielder and Santiago. On the very highest potential crops or where yellow rust has been seen 60g/ha of pyraclostrobin will be added.

What a pleasure to say that the field gate is now closed on winter barley. Two SDHI/azole mixtures have left a very clean crop and our decision not to apply a T0 appears vindicated.

Winter barley performed extraordinarily well last year. Potential appears good this year, but I really cannot see it reaching last year’s peaks. One thing that really stood out last season was the massive size of the leaves across all varieties and I do not see this being repeated this year. Perhaps this will be a season when six row hybrids really stand out.

Pulses have responded well to the rains and winter beans are flowering strongly well. Disease levels appear low. Weevil pressure has been severe in thinner crops in dry cloddy seed-beds.

Let’s hope that we continue to receive meaningful rain over the next two months but that it stops for harvest time!

See more