Start your Autumn field-work with positive harvest management this season
Posted 6 years ago
29/05/2020
Starting your autumn field-work well ahead of combining will avoid this season’s cropping challenges getting in the way of the cleanest, best and most-timely establishment of your next crop, advises Bayer weed control specialist, Thomas Scanlon.
“Min-till growers, in particular, have long appreciated the value of making combining their first cultivation for the most effective straw and chaff incorporation ahead of seedbed preparation,” he points out. “And prompt, efficient harvesting will be more important than ever to give sufficient time for the best pre-planting weed control, not to mention repairing soil damage from the wettest winter in living memory for many.
“For the most-timely harvesting and consistent trash chopping and spreading in a season of such variable crop growth and maturity you need the most positive harvest management as well as best combining practice.
“Undertaken correctly, this can also make a big difference in dealing with weeds that have profited from less competitive late-sown winter wheats, flea beetle-hit oilseed rape canopies and thin spring barley stands struggling from a very dry start.”
The key essential in the positive harvest management Mr Scanlon sees as crucial this season starts up to three weeks before combining with the right pre-harvest spray programme.
He warns that getting the glyphosate timing correct will be especially challenging in oilseed rape crops that have compensated for damage from flea beetle larvae with late-branching and an extended flowering, leading to a wide spread of pod maturity throughout the canopy
With many crops carrying much of their yield lower down the canopy in pods that can be 7-10 days later in their maturity than those near the top, not going in too early with the pre-harvest spray is vital. Not least because each day of seed filling lost typically reduces the average yield by 1-2% and the bulk of the oil content accumulates towards the end of seed fill.
“There is absolutely no advantage in spraying glyphosate before rapeseed moisture levels drop below 30%,” Mr Scanlon explains. “Rather than bringing combining forward it just means crops take longer to dry down. So, it’s important to hold-off on spraying until two thirds of seeds in the part of the canopy carrying the lion’s share of the yield show that classic change from green to brown. Apart from anything else, this will minimise immature ‘red’ seeds in the sample.
“The same 30% moisture level applies to pre-harvest spraying in cereals. This is reached when all the grains from the centre of the ear hold an indentation from a firm thumbnail press.”
Mr Scanlon stresses that heavily-waxed and thick-stemmed OSR canopies, the use of stay-green fungicide chemistry on both cereals and oilseed rape, senescing crops with less-effective translocation, and weather uncertainty all make the choice of glyphosate formulation of fundamental importance too.
“Today’s glyphosates vary widely in their formulations and activity,” he insists. “Particularly so since the withdrawal of tallow-amines which has led to a significant reduction in speed of kill of many.
“The biggest challenge with glyphosate is getting it into the plant. Modern Roundups stand out here for their ability to deal with heavily waxed cuticles, reliability under challenging conditions, and outstanding rainfastness. The drift reduction technologies in Roundup Powermax and Flex are also really valuable with high boom heights and the need for the greatest environment safety. As are their completely clean labels.
“Medium-coarse sprays, together with water volumes, pressures and settings giving thorough canopy coverage and penetration are equally important, with applications early in the day useful in hot weather.”
While there is a statutory minimum interval from glyphosate spraying to combining of 14 days for OSR and seven days for cereals, the time taken for crops to dry down very much depends on the weather.
This means they should only be combined when they’re fit – which may be up to three weeks after spraying in some cases for oilseed rape.
“As well as coming to harvest more promptly and evenly, crops effectively managed with Roundup are invariably easier and more efficient to combine, with valuable savings in time and diesel,” notes Mr Scanlon. “This is especially valuable with the very catchy harvesting weather we’re getting so often these days.
“More consistent crop dryness and lack of green weed growth at combining reduces the transfer of moisture to the grain during thrashing and grain losses too. And it ensures the most effective straw and chaff chopping and spreading.
“Together with faster and more timely combining, positive harvest management can make all the difference in giving your next crop the best possible start as well as making the very most of your current one. Especially so, as part of a well-integrated weed management strategy.
“Do remember, though, that seed crops should never be treated; no amount of adjuvant can make up for insufficient glyphosate; and both pre-harvest and subsequent stubble treatments should be carefully integrated with cultivations to guard against resistance development.”