Crops growing rapidly in good conditions

Most of the spring cereal crop was drilled during the first days of May, and the decent amounts of intermittent rainfall at that time coupled with warm temperatures have meant these crops brairded very quickly and are growing rapidly at the moment.

As well as rapid crop emergence, so weed germination has also been very fast. Hopefully any crops requiring control of annual meadow grass have already been treated.

Spring Barley

To minimise the effects of competition on the crop and optimise the level of weed-control, the herbicide application should be carried out sooner rather than later, once all the weeds have emerged but are still small, and before they begin to compete with the crop for nutrients and light. Product choice depends on the weed type and size present and crop growth stage. Broad leaved wise, Sulfonyl-urea (SU) herbicides will likely be the starting point, controlling a wide range of weeds and are very safe to the crop. However they must always be tank-mixed with another BLW herbicide to control SU resistant weeds (chickweed) and those weeds not controlled by the SU’s (cleavers, fumitory and fat-hen). Ideal partners are Compitox,Minstrel and Starane.I have found over the last couple of years the Spitfire, Foundation mix to be the belt and braces for weed control in spring cereals.

Where the range of BLWs present are limited to chickweed, redshank, fat hen, fumitory and day nettle, the hormone mixture products will work well without the need to tank-mix, but must be applied by GS31. Where the likes of field pansy, forget-me-not, speedwells and corn-marigold are also present however, sulphonyl-ureas products will improve control. Spring barley, spring wheat and spring oats undersown with grass and clover should be treated with TRIAD and where clover is not important MIRCAM PLUS should be applied. If seedling docks, thistles and buttercup are also problem weeds, SPRUCE must be added to the TRIAD to improve control of these also.

With later drilling, there will be a shorter growing season meaning fewer tillers, fewer ears and grains per ear, resulting in reduced yield potential.

A well-timed application of SELON will reverse this effect by encouraging tiller numbers and tiller survival. This treatment must be well timed to maximise its effect, optimum timing for barley is from the 2 expanded leaf stage to beginning of tillering, GS12–21; in wheat the optimum timing is slightly later, 5 leaf to mid tillering, GS15-24. Many crops will already be passed this growth stage and where not yet applied, the SELON should also be done as soon as possible to ensure best effect.

Temporary nutrient

problems

A young plant that is growing extremely rapidly is producing a huge amount of new plant tissue each day. This rapid growth is limited only by the availability of nutrients to synthesise biomass, dependant on soil fertility and the plant’s own root development to take up the nutrients. It is at this time therefore when nutrient deficiencies are most likely to appear, and in doing so, suppress growth rates.

The application of a broad-spectrum trace-element mix along with key macronutrients during this time is a very useful and beneficial way to supplement the plant’s nutrient requirements during periods when availability does not meet demand, most likely to coincide with phases of rapid growth ie. during tillering and as stem extension begins. Application of a balanced and readily available source of macro & micronutrients that is topping up what is being made available from the soil at this key time will minimise the adverse effects of restricting nutrient availability.

Potatoes

The protracted planting this spring has meant most potato crops are only now receiving weed control. This task must take priority as to delay until after crop emergence will set the crop back even further in an already late season. Conditions have been ideal for the use of residual products (Afalon and Sencorex).

Where broad–leaved weed control has yet to be completed and the crop has passed the latest timing for Sencorex a reduced rate of Sencorex tank-mixed with Titus will provide a wider weed spectrum of weed control than Titus used alone and can be used on emerged crops up to 25cm high where the label allows. Scutch, other grasses or volunteer cereals are not controlled by the Titus/Sencorex mix.

Where these weeds become a problem in coming weeks the graminicide Shogun can be applied. Shogun can cause transient yellowing and is therefore not approved for use on seed crops.