Early drilled oilseed rape (OSR) crops benefited from good weather conditions in August giving them an early boost ahead of cabbage stem flea beetle (CSFB) migration, although some crops have started to receive a hammering from the pest.
Covering Hertfordshire, Bedfordshire and Cambridgeshire, Velcourt agronomist Ryan Hudson took the early drilling approach to give the crop the best chance of growing away from CSFB adult grazing.
He says: “Most crops went in August 1-14. They had rain within a week and that was plenty to get them away. Anything planted in early August is up and away and looking fairly well.”
To aid establishment, deeper cultivations were generally avoided, but in some cases were necessary where there was compaction from last year’s wet weather says Mr Hudson.
“I have some places we have put OSR in on the back of the cultivator which we would not normally do as it allows flea beetle to move more freely in the soil profile and loses moisture, at the time rain was forecast mid-August, similar to last year, so hoped it would be enough to get crops away but could not risk planting OSR into compacted soils. Many crops have been direct drilled with Horsch Sprinters and Dutch openers – these crops have been pretty quick at getting away.”
The presence of CSFB had been relatively low until the Bank Holiday weekend.
“In this area, for the last six years CSFB have always arrived around the end of August to the first week of September. True to form we saw no activity until September 1 when I found 70 beetles in one of the water traps although the 11 other traps still show little activity with the cool, wet weather. They were all fairly alive in the trap so obviously landed recently. Prior to that there was only six from the previous week.”
Warm weather forecast for next week (September 7) could see some reasonably high numbers of CSFB arriving. However, once the crop has its first true leaves, its growth can keep ahead of CSFB grazing, Mr Hudson adds.
“This is why I have always tended to get plants in by mid-August. Last year we lost 15 per cent of what was planted to CSFB and the dry weather and all of those were planted in early September as we went into that dry spell.
“This year soil temperatures have dropped a bit quicker. We noticed that in mid-August soil temperatures were 22-23degC, but it dropped by 3-5degC after all that rain which is going to slow OSR development down, along with shorter days for crops planted at the end of August.”
Due to high rainfall phoma is being seen on volunteer crops, and for early planted crops it should be monitored, Mr Hudson adds.
“However, big plants are generally less susceptible, so we have a bit of leeway for when we have to go into control it. There might also be suggestions to use PGRs early on large OSR but in my experience the winter and CSFB does enough regulation and keeping the crop healthy and well fed will be key going into winter to get it away from larvae in January.”
Weed-wise, for early drilled crops, canopies will be closing over soon so any broad-leaf weeds need to be controlled soon and then crop competition takes over, Mr Hudson says.
“Once you get into December and January you need to be assessing what larvae numbers may be in the crop so you can make the decision on crop viability before propyzamide applications. Last year a small percentage was lost to larvae with the main problem being waterlogged soils, late frosts and the dry spring.”
In Yorkshire, early drilled crops were looking ‘fantastic’, although shotholing from CSFB is starting to appear on some farms.
Chris Dickinson, technical manager at Agrovista says: “The early drilled OSR is up and away at 4-6 leaves now. To this point we have not sprayed anything for flea beetle, but I saw my first severe shotholing yesterday (September 3).”
The initial wet weather plus a start fertiliser has really helped crops along, he says.
“At least until now it has been quite a pleasure walking OSR. Interestingly, conventional varieties have really liked this weather and have been out the ground within a week, but hybrids have been more like seven-10 days and are a bit more gradual. Conventionals have been noticeably quicker.”
Keeping pests at bay will be the main focus to keep plant vigour and survival up ahead of winter, Mr Dickinson says.
“A bit of fertiliser is good but making sure you get a crop established before you invest too heavily is important. Anything that is at 2 true leaf is probably going to have be sprayed [for CSFB] - It seems quite severe what we are getting.
“Slugs have also been quite a big issue due to the rain we have had so keeping on top of them will also be important. Pigeons are an ongoing problem.”
Volunteers will also require careful management soon, he adds. “If you leave them too late you will soon end up with a problem.”
Although there are still a few weeks left of the OSR drilling window, Mr Dickinson is advising his growers to quit while they are ahead.
“Unless it is really good conditions and the weather is really going to be in our favour, especially on heavy land, let us not just puddle OSR in.”