19 January 2001

First winter strike needs care

BE prepared to protect winter wheats against septoria earlier than usual and do not stint with fungicide on thin stands, agree Bill Clark of ADAS and Dick Neale of distributor Hutchinson.

Mr Clark fears many late sowings may rush through spring growth stages and the optimum TI timing may be missed. Thin crops will need all the help they can get.

Mr Neale says that crops drilled before Oct 10 are already over-thick and loaded with Septoria tritici while those that went in after November are generally struggling. "Their yield potential needs maintaining, as they form a high proportion of many growers crops."

Twist (trifloxystrobin), which Bayer recently bought from Novartis (now Syngenta), means many growers with well established wheats can consider breaking the mould of a traditional three-spray programme. "The protectant fungicides persistency, up to 65 days in Hutchinson trials, allows it."

By starting at stem extension (GS30) with a good dose of the strobilurin, followed at flag leaf just visible (GS37) and ear half-emerged (GS55), Hutchinson trials suggest an extra 1.5t/ha (12cwt/acre) can be achieved.

But management needs changing for best benefits. Crops must have been drilled in early September at very low seed rates and be high potential varieties. It also means being spot on with nitrogen.

Mr Clark fears that in a lot of late drilled wheat infected lower leaves 3, and to some extent 4, will pose a real threat to the upper parts of the plant once they become infected. That is because leaf 3 is likely to emerge before GS32, he warns. "Many growers dont appreciate this." He advises spraying sooner rather than later.

Trimming fungicide rates is inadvisable, he adds. "There is a lot of evidence to show thin crops need fungicide inputs as much, if not more than thick crops particularly at T1." &#42

Timing is everything… Fungicide spray timings will need extra attention this year, say Bill Clark of ADAS and Dick Neale of distributor Hutchinson.

New dual fungicide

Sphere, a co-formulation of trifloxystrobin and cyproconazole, gives growers a competitively-priced fungicide to control all wheat and barley foliar diseases, says Bayers Neil Waddingham. Price will be less than buying the fungicides separately. Mr Neale says two years of trials show the new product out-yields other strobilurin-based compounds under heavy disease pressure.