Pod sealants

There has been much debate in recent years about the benefits or otherwise of pod sealants for oilseed rape. Why farmers can’t harvest the damn crop when it’s ready, I’ll never understand. Then you wouldn’t need them. (Pod sealants, not farmers). Not to fret, hope is on the horizon. I met a farmer recently who had sold three fairly large combines and got one with a 35 foot header (you’ll be able to spot it, it’ll be the one with a tree embedded in the knife at either end of the cutterbar). If everyone had one of those, surely there would be no more delayed harvesting? You’d be able to harvest the rape over lunch. One day we’ll only need one combine per county. Maybe two for Yorkshire.
Anyway, pod sealants enable growers to plant oilseed rape on a block of land twenty miles from the farm and not have to worry about the pods shattering before the combine gets to it just after Christmas. Sorry, should have said ‘allegedly enable..’ In all seriousness though, many growers swear by them and in the final analysis they probably fall into the category of any number of wetters, stickers, penetrants etc, that where ‘there will always be a marginal situation where they will prove their worth’. A bit like growth regulators, then.
Logically it doesn’t make sense. If most farmers are spraying at 100-150 litres/ha water volume, how can you deposit enough glue on all the pods in a dense rape crop to stick them all shut? How do you get the spray to cover the whole pod rather than just the top half it alights on? (Probably systemic. Now there’s a concept: systemic glue).
Whatever one’s cynicism about them, we managed to produce a trial result in 2009 that showed they work. Yes, we hit that million-to-one situation. OK, thousand-to-one. Hundred-to-one?
The manufacturers and dealers believe in them of course. Back in the 1980s, when one very small part of the fossil record of TAG-part-of-the-NIAB-Group was the Cotswold Cereal Centre, we had a rape trial site at Church Farm, Coates, near Cirencester, which was managed by one Jim Boyt. He’d sprayed Spodnam (the grandaddy of pod sealants) on one of his fields and was disappointed with the result. He phoned Mandops to complain and Michael Sampson himself (owner of the company) came out to Gloucestershire to look at the problem. To Jim’s amazement he got on all fours and crawled into the dense, leaning crop. A couple of minutes later he crawled out, chewing two or three pods. Removing them from his mouth, he told Jim ’Sorry, I can’t support your claim, you only applied half rate’. He was right.
I don’t think there’s much debate about whether they do to pods what they claim to. Many of us have seen the pictures of rape pods tested by ‘extensiometers' (sic) and other gadgets showing that when treated they don’t break, snap or split as readily as untreated pods. It’s just a case of knowing if you’ll need that effect.
In the end you have to look at the cost of the chemical, the application costs, the crop damage costs, if any, and balance that against a potential, or feared, yield loss through pod shatter. Inevitably there will be situations where they will be of tremendous value, paying for themselves many times over, and also situations where the money will be wasted. It’s a bit like insurance. Or growth regulators.

The Arable Group

TAG is the country's largest independent agronomy service, we have over 20 trial locations throughout England and the information generated at these Centres is used to provide the TAG advisory service. We do not sell seeds, fertilisers, or agrochemicals; our mission is to produce impartial agronomic information on the entire range of crop types, cultivations, spray technology, environmental schemes and agronomic inputs.

In 2009 TAG integrated with the National Institute of Agricultural Botany to form the NIAB Group.