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Crop Crack 28.03.09
By Wendy Fearon
CEREALS
The wintry conditions over the last week have hampered drilling of spring crops and the application of fertiliser onto autumn sown crops. Most winter cereal crops are still green but will very quickly look for nitrogen as soils warm up.Rhynchosporium is present on more susceptible varieties of winter barley with very little mildew apparent.
Septoria is also present on winter wheat but seems to be confined to older leaves. Adjust and manganese are now being applied onto winter barley crops along with a herbicide if required.
Cleavers and chickweed are very strong in some early drilled crops and Starane XL should be applied to control these. Large fumitory is also present in some crops and CMPP should be applied as soon as possible to achieve good control.
HORTICULTURE
Growing vegetable crops is becoming increasingly more difficult as more products disappear from the market. The loss of trifluralin and the imminent loss of Ramrod is a major blow, Ramrod can be used on farm up until March 2010.Without these two actives it is going to be very difficult to achieve weed control in brassicas.
There is also very little which may be used in Turnips with Butisan being the preferred choice and is best applied pre-emergence of the crop and weeds.Butisan is weak on fumitory, day nettle,knotgrass,fat hen and red shank.Pyridate better known as Lentagran has been resurrected with approvals for brusselsprouts ,cabbage and onions but also has a gap in the weed spectrum including knot grass,AMG,chickweed,charlock,mayweed and shepherds purse. If Pyridate is to be applied it is essential to have adequate wax on the leaf.
There is also a SOLA for the use of Clomazone in outdoor cabbage, sprouts and broccoli either pre-emergence of drilled crops or post-transplanting but before weed emergence in transplanted crops.Clomazone adds chickweed, shepherds purse,nettle,groundsel amongst others to its weed spectrum, adding to the activity of other residual herbicides to which it may be tank mixed.
Carrots are another crop badly hit by the loss of weed control options. Carrots and parsnips are very susceptible to weed competition and good control is essential. If applying Afalon this season a maximum of 1.35lt/ha is allowed and unless soil is moist activity may be poor at these low rates.
Flexidor,Sencorex and Defy have SOLAs (off label approvals) but are applied at the growers own risk. When using herbicide mixtures on carrots take care, especially on very light soils and in hot conditions. A pre-em or early post-em treatment followed by a later post-em sequence is recommended for programmes.Activity of residual herbicides is reduced on soils with more than 5-10% organic matter.
Buds are beginning to appear on fruit trees and the humming of sprayers has already been heard this season. The first fungicide will probably include Scala and Dithianon as this will give good translaminar activity.
POTATOES
It is important for potato growers to ensure moist clod free ridges to achieve adequate weed control. Weeds must be treated pre-emergence or when they are small as products such as Retro, Basta or Shark are not as good as PDQ on big weeds. Retro can be weak on big grasses, Shark has no grass activity and should not be applied beyond ridge cracking.Basta has good all round weed control and should only be used pre-em of the crop and works best in bright sunlight.Afalon must not exceed 1.35lt/ha and will struggle at this lower rate therefore should be tank mixed with Sencorex so long as the variety is tolerant.
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