Crop Watch: Herbicide Shortages and Winter Bean Planting


Recent rains have been welcome, particularly in the dry north, where concerns were growing about the effectiveness of residual herbicides for early-planted cereals.

A shortage of glyphosate was also affecting weed control plans, with the co-formulation of glyphosate and 2,4D being used to fill part of this gap.

Thoughts are now on planting winter beans, and limited supplies of propyzamid are forcing changes in herbicide strategies.

North: Mary Munro

AICC / Strutt and Parker (Perthshire)

After one of the easiest harvests in recent times, I was worried that the fall seedlings were plagued by endless rains. So far this has not been the case and the rain we have had was welcome.

It is not normal to see clouds of dust coming out of the potato diggers, but things were getting very dry.

See also: The Soil Health Scorecard: What It Is and How To Use It

Autumn crops got off to a good start and rapeseed in particular benefited from early sowing in warm soils. Most crops are in the six to seven leaf stage.

The next job will be to spray Curb (propyzamide) once the temperatures drop a bit more, and I’ll be looking to do that over the next 10 days.

Most grains have had their residual herbicides. Some of these will have been applied in very dry conditions, which may reduce effectiveness, so growers should keep in mind that follow-ups for grasses may be necessary. This shouldn’t be a problem for the wheat coming in now, because there is a lot of moisture on the surface.

Oat volunteers

The most advanced wheats are tillering. I plan to withdraw volunteers from the oats at the next opportunity.

The timing of agrochemical applications is of minor concern compared to the broader issues of fertilizer pricing and access, product availability (such as curb and glyphosate), and all of the issues associated with transportation. It has been a long time since we have seen supply pressure at this point, and producers need to adapt to this scenario and do what they can to secure their inputs.

Given the concomitant rise in grain prices, the nitrogen balance rates have not changed dramatically – in many cases a downward adjustment of 10 to 15 kg N / ha is all the fine tuning that is necessary. There is little sense in reducing to the point where the yield is drastically reduced, especially when grain prices are high.

In my opinion, there is no prospect of a significant price drop anytime soon. We have the impression that Brexit is starting to make its mark.

West: Stephen Harrison

AICC / Agronomy of the South West (Avon)

After a series of very difficult planting seasons, it was a pleasure to watch the crops establish themselves under ideal conditions. The seedbeds are still good, except for a few plowed on heavy soil which has dried out.

Emergence here is variable and some herbicide damage is evident. The maize harvest is almost complete and the first crops for crimping have been cut at a very acceptable humidity level of 36%.

We seem to have caught up with the eastern counties when it comes to herbicide resistant black grass. If I’m perfectly honest, the seedbeds are a bit dry and this week’s rain is welcome for the herbicide activity.

Late deliveries of seeds have been a recurring problem, causing frustration. Thousand kernel weights have often been low, with some tinkering in the required seed rates. To be fair, the smaller seed seems to establish itself satisfactorily.

No untreated farm seed was used, as each sample tested had very high levels of michodochium.


The first colonies of wingless aphids (mainly the oat cherry aphid) were observed. The winter barley from the September emergence will receive an insecticide shortly. The persistent mild weather will only make the problem worse. Remember to restart the T170 countdown as soon as the cultures have been processed.

Approaching T170 should be a trigger to start looking not to spray. Irresponsible use of pyrethroids will simply speed up resistance and damage the beneficial ones.

Rapeseed crops sown in early to mid-August develop large canopies, even after plant growth regulators. Phoma lesions appear and will accelerate in the rain.

Please use the nitrogen from the crop next spring – optimizing nitrogen supplies is of even greater importance this season. There was talk of price parity for wheat and nitrogen; it’s out the window and even rapeseed can’t match it.

The winter beans are now being sown. The predominantly farm-saved seeds are of good quality with a high weight in thousands of seeds, germination over 90% and minimal seed-borne disease.

The trend towards drilling rather than plowing continues.

East: Becky Finbow

Agrovista (Norfolk / Suffolk)

Finally, it looks like we’re having a little more ‘normal’ fall, with some of the best seedbeds we’ve seen in years.

The saying “don’t sow unless you can spray” has been repeated by myself and by farmers, illustrating how important the application of pre-emergence herbicides is for the control of black grass and ryegrass. in winter cereals.

Less than ideal fall conditions over the past two years have prevented the application of many pre-emergence sprays, forcing the use of contact chemistry.

Unfortunately, these herbicides – predominantly sulfonylureas – are less and less effective with the continued increase in resistant populations of ryegrass and black grass.

Yellow sticky traps were placed in the early sown wheat fields to accompany the use of the sum T to calculate the first spray of barley yellow dwarf virus. In Norfolk, esfenvalerate or lambda products are now applied at the two leaf stage to control aphid populations.

However, where farmers sowed Wolverine – the first UK variety resistant to barley yellow dwarf virus – insecticide spraying is not recommended, as yield would not be affected, even under pressure situations. the highest.

Slug threat

The OSR’s successful harvest left behind waste which, along with the humid and warm conditions, contributed to large slug populations this fall. Traditionally, post OSR cereals have been the main concern, but on heavier soils this year I am also seeing slug damage on second germinating wheats.

Ferric Phosphate was applied shortly after seeding to the crops after OSR but I continue to monitor as additional application may still be needed.

With wheat planting well underway, farmers are starting to think about their winter bean crops. Seeds stored at home should be tested for nematodes, ascochytes and germination to ensure quality before sowing.

Beans provide a great opportunity to overcome grasses and broadleaf weeds, the subsequent seeding window allows for a stale seedbed and a good variety of pre-emergence herbicide choices.

In Suffolk, where black grass is the primary concern, propyzamide will be the backbone of my pre-emergence program, with the addition of pendimethalin plus or minus clomazone for broadleaf weeds.

© Tim Scrivener

South: Richard Harding

ProCam (Sussex)

The very volatile weather of the past week on the Downs was widespread, with very little fieldwork done until the middle of last week on heavier soil types on the Weald.

Precipitation ranged from 40 to 50 mm to 78 mm in three days. This precipitation delayed both planting and spraying of pre-emergence herbicides, but each day of delay also reduced the pressure on the black grass.

As drilling is done later, the pre-emergence stack used to date – Avadex (tri-allate), fluefenacet, diflufenican and prosulfacarb + glyphosate – will now be simplified, where possible, leaving easier to control broadleaf weeds such as mayweed, groundsel or volunteer beans in the spring.

Cereals pierced earlier that have one to two or more leaves are scanned for aphids. Yellow sticky traps are also useful to help monitor aphid levels, used in combination with the 170-day degree threshold for these crops ( and depending on the crop emergence date.

Glyphosate shortage

With glyphosate being very rare this fall, in addition to being less active on broadleaf weeds and OSR regrowths, a co-formulation of glyphosate and 2,4D helps close the gap and protect any pure glyphosate. which could be left in Stock.

However, in some situations, such as bean regrowth, it may be more economical and effective to control this weed in the next grain crop.

Winter rapeseed crops vary widely, ranging from the three to four true leaf stage to well over 30cm tall in companion crops which now have a white / purple tint from phacelia, buckwheat, and flax.

Cabbage stem flea beetle levels are generally low, although larvae are just beginning to be found in plants, albeit at very low levels.

With the first winter bean crops being planted and a shortage of propyzamid this season, higher rates of prosulfocarb and pendimethalin will be used for the pre-emergence herbicide, adding clomazone where cleavers are a problem. high risk.


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