What a relief to have some rain and some warmer nights last week. Early-drilled wheat crops will have received their T1 spray, and the applications for the later drilled taking place. The threat of yellow rust has declined as whether conditions have not been favourable for its development. The most susceptible varieties received a T0 fungicide.
The biggest threat is septoria, where inoculum level at the bottom of the crop is high – do not be tempted to reduce rates of triazoles, thinking that disease levels are low, as this is the most difficult disease to control, due to triazole resistance. You can not play catch up with septoria. Yellow rust can be found in the spring wheat AC Barrie, which is quite disturbing, so a triazole has been added to the T0 fungicide.
Frost damage to oilseed rape flowers can be found. Hopefully, the plants will be able to compensate. All sorts of nutritional disorders are showing up due to crops going through rapid stem extension and not being able to take enough nutrients up. Cold growing conditions are not helping either. Split stems can be found which is caused by rapid growth and not being able to take up enough nutrients, especially boron.
Where a yellow bud fungicide was not applied a mid-flowering fungicide will be applied, soon. Where a yellow bud fungicide has been applied these will be treated two to three weeks after the stem extension spray. Uneven flowering crops will probably require two shots at sclerotinia control, as in 2007 it was all the late and uneven flowering crops that got infected by a late attack.
It will be interesting to see if there is any difference in sclerotinia levels in a min-till versus a crop established by ploughing, which is being monitored by Dr Peter Gladders.
The hard frosts of February have certainly stimulated the germination of spring wild oats. They are not only emerging in open winter cereal crops, but in sugar beet, peas and spring beans. Spring crops treated with trialate seem to be clean at present.