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WESTCOUNTRY FARMER: Right mix will ensure crops are disease free

By Western Morning News  |  Posted: March 19, 2014

WESTCOUNTRY FARMER: Right mix will ensure crops are disease free
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Sprayers will be out in force over the next few days as disease control in winter cereals gets into full swing.

The jobs list on arable farms in the South West has been growing, with fungicide applications to control high levels of disease foremost in growers’ minds, said Cornwall-based Agrovista agronomist Martin Stuart.

“Winter sown crops got away relatively unscathed in most areas. Crops drilled in late September and early October look good, as do most of the remaining 30-40% sown in the back end of October and November.”

Some coastal wheats have suffered salt burn after the recent storms. Re-drilling was the only option where significant crop loss had occurred, Mr Stuart said. “However, given where we were last year, arable growers are not complaining.”

Vegetable and daffodil growers in Cornwall have also faced tough harvest conditions, he added. “Soil conditions have been very poor for machinery, and crops suffered from hail damage so growers had to be quite selective.”

For early potato planting, growers that had established a crop under plastic could expect very high prices by Easter, Mr Stuart said. “The benefits of plastic diminishes with later plantings, especially with soils this warm, so produce will come in a rush.”

Disease control was a priority for winter cereal growers across the region. Many barley crops further west had not received the first fungicide spray (T0) due to poor weather. Growers should wait until crops were at T1 (growth stage 30) and increase rates.

“T1 is the most responsive timing, aimed at protecting leaf 3 and eradicating disease on older leaves. I’ll use Jaunt – it contains fluoxastrobin, prothioconazole, and trifloxystrobin, providing good control of rhynchosporium, the key target, and net blotch. I’ll increase rates on crops that missed T0 from the usual 0.5 to 0.65 litres/ha. I might use a SDHI like Siltra Xpro on a very rhyncho-susceptible variety such as Maris Otter.”

Mr Stuart will add a low-rate Canopy (mepiquat + prohexadione) or half-rate chlormequat growth regulator to improve tiller retention and rooting.

Most wheats would be due a T0 fungicide in the next few days. “We are seeing very high levels of septoria, even for the west. A triazole, plus 1 litre/ha of chlorothalonil to boost protectant activity, will be required in many crops. Ennobe contains epoxiconazole and also prochloraz, which increases control of septoria strains that are becoming less sensitive to epoxiconazole. Ennobe’s formulation also improves epoxiconazole’s eradicant activity.”

He will add Canopy, with chlormequat as necessary, to improve rooting and tiller retention. “However, I may leave a growth regulator on more backward crops until T1.” Lush crops on very fertile sites might receive trinexapac-ethyl (eg Optimus, Moddus).

Some later-drilled winter cereals on wet heavy land in Devon and Cornwall had not received any herbicide. “Normally late-drilled crops would be clean. But the mild winter has encouraged strong weed growth.”

Herbicide should be applied as soon as soils could carry a sprayer, he advised. “A full rate of Herold, which contains diflufenican + flufenacet, will do a good job on annual meadow grass in barley. I’ll also add an 80% dose of Finish – it controls a wide range of broadleaved weeds and helps grassweed control.”

For wheat, Mr Stuart advises a three-quarter rate of Othello (diflufenican + iodosulfuron + mesosulfuron) plus Finish.

Growth regulation would be vital in oilseed rape crops this season. He recommended Caryx (metconazole and mepiquat chloride) at 0.7-1litre/ha. “It is very good at reducing lodging risk when applied at stem extension or for manipulating the canopy to improve light penetration when applied at stem extension or late green bud.”

On less forward crops split applications of straight metconazole (eg Sunorg Pro) at green and yellow bud would suffice.

Other crops – Grassland:

Check weed growth in reseeds.

Assess potential for dock control in leys in early April.

Apply Doxstar (fluroxypyr + triclopyr) but allow 28 days before cutting to allow herbicide to translocate to roots.

Docks must be actively growing at time of spraying.

Other crops - Oats:

Crown rust can be found - If weather remains warm apply a low-cost triazole eg cyproconazole (Centaur) in late March.

Martin Stuart is an agronomist advising for Agrovista in Cornwall (Martin.Stuart@agrovista.co.uk)

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