Crop Watch – West/SW

Tim Horton – Cleanacres

Recent showers will have encouraged Septoria tritici to spread up the plant on to emerging leaves. For most crops in the West, leaf three is now emerging, so the timing of the T1 spray will be critical to keep this disease at bay.

Leaf three is the main target of the T1 fungicide. Where a pre-T1 has been used, this will reduce the initial disease pressure on the crop, giving growers a little flexibility in their T1 timing. But the recent spread of septoria will require a good curative element in any fungicide treatment.

As a multi-site fungicide, including chlorothalonil with a triazole is a good choice early on, and provides a useful anti-resistance strategy. But septoria is only part of the disease matrix crops in the west will be facing.

The damp conditions will have brought on eyespot infection, especially in early-drilled crops, second wheats and susceptible varieties (Soissons, Solstice and Hereward). I‘ve also seen plenty of mildew on some susceptible varieties.

This will generally mean a robust T1 is needed, and the addition of prothioconazole is particularly well-suited to the current range of problems, being a good septoria and eyespot product.

Winter barley crops have reached GS31 and need the T1 spray. This is the most important fungicide timing in barley, setting up the potential for the whole crop. Net blotch, particularly in Pearl, and rhynchosporium are the main targets.

For both wheat and barley, current warm weather and soil moisture will encourage rapid growth, so I‘d advise adding an early growth regulator to the T1 fungicide.

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12 April 2005

Joss Wood – Independent Arable Advisor
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Winter wheats are looking well, but starting to appear “hungry” for their first main nitrogen split, which is now being applied.

Magnesium and manganese deficiency are showing up widely, especially on the high pH soils of Dorset and Wiltshire, and are receiving suitable trace elements at T0/T1 timing, to help correct this.

Recent heavy rain has increased the pressure from Septoria tritici, justifying the use of a T0 fungicide on early drilled susceptible varieties, together with cleaver control where necessary.

A further flush of wild oats is emerging, and will be controlled atT1 fungicide timing. Winter barley is also under pressure from Rynchosporium due to recent rains, increasing the urgency to apply T1 fungicides during the coming 7-10 days, at GS 31/32.

Winter oats are looking well, but beginning to look starved of nitrogen – not altogether a bad thing in view of the high level of mildew present six weeks ago, which has largely been “controlled” by recent cold weather.

Nitrogen top dressing is planned for a week‘s time. Crown rust is not present yet, but at GS31+ is likely, especially on the Isle of Wight, where control is essential at the very first sign of the disease!

Spring crops have had the best start for many years, with strong, even emergence. Spring barleys are now at the 3-4+ leaf stage and have received Nitrogen top dressing. Plan to spray out flush of weeds at earliest opportunity, together with early Growth Regulator/Manipulator.

Spring beans and peas have established well and are being monitored for bean weevil and thrip – little activity at moment. No further action planned on winter oilseed rape until early to mid flowering.

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5 April 2005

Bryce Rham – PROCROP
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Sugar Beet:
Some 75% is now sown, with earliest crops at cotyledon stage. Slugs and leatherjackets have been found in some crops (one crop needed an immediate application of chlorpyriphos). Second nitrogen doses should be applied as soon as crop is at cotyledon stage.

Winter OSR:
Most forward crops (Winner & Castile) are starting to flower. Crops are now receiving an application of Folicur (tebuconazole) + Mavrik (tau-fluvalinate) for growth regulator purposes and pollen beetle. Always apply in late afternoon and warn local beekeepers 24hrs in advance when spraying insecticides on rape.

Second nitrogen application should be finished by end of this week (w/e 10/04/05), before the crop gets too tall.

Winter Barley:
Most varieties are now at GS 30-31. Net blotch incidence is about 5%, and rhynchosporium at lower levels. Mildew is also evident, but cold February/ early March weather has generally reduced incidence.

Winter wheat:
Most forward crops seen this week are at GS 32 (Claire after potatoes sown September 10). Einstein sown at the end of September is also forward at GS 31. Penetrating eyespot is visible on Einstein in some situations. The first nitrogen applications began on March 28.

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29 March 2005

Neil Donkin – Countrywide
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There is great variation in wheat disease levels. Early-drilled crops, approaching GS 30, are carrying high levels of septoria tritici on older leaves. This needs to be subdued with a T0 fungicide.

Mildew levels vary depending on variety and location; Claire and Solstice in sheltered fields are particularly bad. Crops often grow away from early mildew, so unless clearly active, re-assess the problem in time for T1.

Later-drilled crops are prostrate with few, spindly tillers; split rates of chlormequat will help tiller development here.

Barley has net blotch and rhynchosprorium and it will soon be time for T1 treatments; 10mm of rain in the last two days has increased the risk from both diseases.

Check oats for active mildew; it needs controlling now.

Manganese deficiency is showing up. Manganese can be added to T0 treatments and again at T1, if necessary.

Oilseed rape has changed dramatically in the past two weeks. Many crops are approaching green bud and while disease levels are very low, in many cases, because of plant density, they require growth regulation.

Watch out for pollen beetles; on one farm this week I found ten or more in almost every flower head.

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22 March 2005

Tim Horton – Cleanacres (part of Masstock Group)
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Warmer weather after the recent cold snap has brought crops racing on. Forward wheats have finished tillering and started stem extension, so the priorities should be early disease control and growth regulators.

There is plenty of septoria inoculum in crops, and we‘re strongly recommending growers apply a T0 triazole or chlorothalonil. Also check crops for mildew, since levels were high before the cold snap.

Some frost lift has occurred, particularly on chalk soils, and here rolling will help anchor plants.

Patchy or backward crops will benefit from an early split PGR during tillering to improve rooting and even up growth. An early dose of nitrogen will help them approach target tiller numbers.

Outstanding blackgrass treatments must be applied at the earliest opportunity since control will decline as weeds reach the end of tillering.

Oilseed rape crops are at last starting rapid stem extension – later than last year, due to recent cold weather. Growers may need to apply an appropriate fungicide to check growth.

Nitrogen and sulphur dressings should be going on, and growers should check potash and boron levels.

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