AHDB has recently updated guidance to help growers target the appropriate use of glyphosate in the run up to harvest.
Updated as part of a new stewardship initiative, the information can be used alongside label recommendations and harvest interval restrictions to help keep crop residues to a minimum.
Central to the guidance is a series of visual tests which can be used to estimate when grain/seed has less than 30 per cent moisture content to help target any application.
In oilseed rape, glyphosate applications can be used to facilitate direct combining, normally within 21 days of application.
The following visual test can be used to estimate when seeds have less than 30 per cent moisture content.
Step one: Select an area of the crop that is representative of the field as a whole. Then choose an area of canopy that is typical of the maturity of most of the crop. Depending on the canopy, this may be pods in the middle of the main raceme or on the side branches. At random, pick 20 pods from several plants.
Step two: Open each pod and observe how many seeds have changed from green to brown. If this change is observed in at least two-thirds of the seeds per pod in at least 15 of the pods picked, then the earliest correct stage for spraying has been reached. Typically, the crop should be sprayed within four days. If the weather is very cool, however, this can be extended to seven days.
Step three: Check the assessment is representative of the entire field (repeat steps one and two, as required)
For cereals, glyphosate applications can reduce green material, including immature tillers, and improve harvest efficiency and grain storage. This can be particularly valuable in wet seasons. Grain has less than 30 per cent moisture content around the ‘hard dough’ stage (Growth Stage 87) and normally occurs one to three weeks prior to harvest.
The following visual tests can be used to guide whether a crop is at or below 30 per cent moisture content: