Crops moving rapidly through growth phases despite dry weather conditions

Crop Crack logo
Crop Crack logo

I think it would be fair to say conditions over the last couple of weeks make farming a much more pleasant occupation.

Crops have moved rapidly through the growth stages and consideration should now be given to pre harvest treatments of glyphosate. Winter wheat and spring barley crops have been badly affected with dry conditions with many crops senescing prematurely.

The continued warm weather has encouraged high populations of aphid in all crops but it is important to note that unless absolutely necessary an insecticide should not be applied as bees are very active at present. The main period of egg laying by the first generation of carrot fly is now over.

Second generation flies will appear from early August and foliar insecticide sprays targeting the adult will be needed at that time. Much of the winter barley has now been harvested with respectable yields given the dry conditions.

Potatoes

Due to the considerable amount of new growth being produced at present, it is essential the product being used is fully systemic to properly protect the new leaves being put on between applications. Later planted crops are at higher risk as they produce more new growth between applications than earlier planted crops, at a time when the level of inoculum in the air is progressively increasing.

Of the fully systemic fungicides, only those based on propamocarb appear to effectively control the A2-13 genotype. INFINITO containing propamocarb and fluopicolide controls all strains of blight, with no resistant genotypes found to date. Although a translaminar product, Syngenta have shown that REVUS also gives very good protection of new growth, and offers an alternative mode of activity to propamocarb.

As the crop canopy closes across the drills, the crop starts to initiate tubers. From this point on these daughter tubers are vulnerable to infection, so fungicide selection must also consider introducing tuber blight control, spread by zoospores being washed off any infected leaves or stems.

During the main canopy development phase the rate of new growth is extremely rapid. This places a huge uptake demand on the uptake of all nutrients, and in conditions of such rapid growth any nutrient that is limited in availability will suppress haulm growth, and as tuber initiation begins, tell the plant to form fewer tubers also. Manganese, sulphur and magnesium are three of the potentially most limiting trace elements, and timely application of these nutrients in an immediately available foliar formulation will offset this yield limiting effect.

Make sure nozzle type used is correct to ensure sprayer pressure, droplet size and water volume applied are as per the label; these factors are as important as product choice in terms of achieving good coverage of the foliage. Inspect and calibrate nozzles regularly to maintain performance.

Pre Harvest Glyphosate

With the recent sunshine hastening the ripening of cereal crops, thoughts will now turn to grain quality, moisture levels, and ease of harvesting. This year in particular grasses and other weeds are a real problem in many fields. Pre harvest application of glyphosate is an essential tool to improve the efficiency of harvesting, giving a range of benefits, grain moisture, faster harvesting and sooner baling of straw.

Note however, do not use glyphosate on any crops where seed may be saved for re-sowing.

Independent trials carried out over a number of years in GB looking at the effect of using Roundup in various replicated treatments consistently show moisture contents being reduced by 2.0-2.5% at harvest compared to plots where no treatment is applied.

With a wide range of glyphosate products available, which offers the best performance in the field, and best value for money? First off, it is not the price per drum that should be compared. With different formulation types having different strengths of active per litre and therefore different rates of use, it is the price per acre treated that should be compared, and what level of performance is being obtained from each. Glyphosate itself is not very soluble therefore it depends very much on the salts and wetter’s to enhance its performance. Tallow amine products de-wax the leaf surface and cause cell damage, whereas the ROUNDUP ENERGY wetter does not damage the leaf surface, so the uptake of glyphosate into the leaf is much more effective than with the ETA product, and the level of long-term kill achieved from ENERGY is significantly greater.

The potassium salt in Roundup Energy is also taken up significantly faster than the isopropylamine salt; as a result ENERGY is rainfast within one hour of application and cultivation can commence as soon as two days after application whereas the IPA glyphosate products need a minimum of six hours to be rainfast and five days minimum before cultivating.

Application should be made once the grain moisture gets down to 30% or below, ideally 10-14 days (and not less than seven days) before cutting. An easy and reliable test to estimate this 30% moisture level is to press the thumbnail into a number of grains; if the indentation holds on all the grains the crop is ready for spraying.

Grassland

As much of the grassland acreage went untreated for weeds prior to both first and second cut it is important to inspect fields intended for cutting and grazing in order to allow the spray interval for stock rotation.

Docks are the most damaging weed which infest our grassland farms. Over the last number of years Forefront has been the outstanding product for controlling docks in Northern Ireland. In addition to docks it will also control nettles, thistles, buttercups, ragwort and chickweed giving a complete clean-up in your fields.

With many fields showing the effects of the last couple of wet years, rushes have become a major issue on farm. Rushes are relatively easy and inexpensive to control. Spray rushes when they are green and actively growing, and always add a wetter/sticker (e.g. Activator) to enhance uptake into the plant. Due to the shape of the rush, there is always potential for spray run-off, which the wetter will help to prevent. The most popular products for controlling rushes in Northern Ireland include Agritox and MCPA 500.