Archive Article: 2001/10/20
"We are seeing more and more leaves chewed off at ground level in early drilled wheats after grass leys and grassy set-aside. I am having to recommend seed treatment with Secur to prevent crop losses."
Also localised, gout fly have had a stab at reducing populations by eating out the central shoot. But if no more than a quarter of plants have gouted shoots, there are probably enough left, stresses Mr Oakley. The threat is now dwindling.
"The gout flys small, white cigar shaped eggs will all have been laid by now on the upper leaves of wheat plants. You may see some of the tiny, yellow larvae if you open up the shoot, but the damage is already done. So unless the pest has taken out too many plants, theres nothing you need to do."
Slugs are a different matter. Slug activity is high where seedbeds were cloddy at drilling, particularly where rain has recently fallen.
The only other pest to cause concern is the wheat bulb fly, a particularly high risk after potatoes, beet and set-aside fallow. While problems wont show up until the New Year, its time to assess the risk before its too late. Any fields at risk should be sampled, ideally, before cultivations disturb the soil, he warns .
Egg counts in soil will indicate the likelihood of later infestation. Early counts suggest average levels this season, though the risk is higher than in previous years in potato growing regions of Scotland, says Dr Evans.
If there is a history of the pest on the farm, or egg numbers exceed the threshold, he and Mr Parish recommend growers use the seed treatment tefluthrin (Evict) on late sown crops rather than wait until damage appears and use an egg hatch or a deadheart spray. Evict and follow-up sprays work best if seed is drilled to less than 40mm (1.5in) and the seedbed is consolidated, according to the results of a small, continuing trial carried out by ADAS and Bayer.
Turning to diseases, winter wheat drilled exceptionally early, as some were in the south, may be at greater risk from mildew as the autumn progresses. Oilseed rape is in more immediate danger, from phoma in the south and light leaf spot in the north and Scotland.
The first phoma lesions appeared a few weeks ago in the far south, says Mr Power. The inoculum came from neighbouring rape stubble, which is becoming a lower risk as cereal drilling progresses. Infection can take only 10 days from start to finish, he warns.
If lesions can be found on 10-20% of plants, he advises starting a two-spray programme four to six weeks apart of either flusilazole and carbendazim (Punch C) or difenoconazole (Plover). Half rates of each should hold the disease, he adds.
In Scotland, where light leaf spot is high risk, Dr Evans is recommending Punch C or tebuconazole (Folicur) at this stage, the optimum timing for control. There is a large reservoir of inoculum and the weather is favouring disease development.