Be aware of these “watch-out” points or pitfalls now drilling of winter wheat crops has slipped later due to unsettled weather, says Nigel Scott.
1. Don’t drill based on seed weight – use seed numbers
Seed rates need increasing to offset the shorter tillering period when drilling later. But big variations in seed thousand grain weight this season make it particularly important to drill in seeds per square metre, he stresses, not in kilograms of seed per hectare. Using 350 seeds per square metre as an example, a thousand grain weight of 52 grams requires 182kg/ha of seed to achieve this, but a thousand grain weight of 64 grams requires 224kg/ha – almost 25% more.
2. Don’t over-stretch seed
The need to increase seed rates with later drilling is complicated this season by a seed shortage. Added to this, some seed carried over from last season has dropped in its percentage germination – some to as low as 60%. Consider using home-saved to make up for shortfalls. But don’t leave it exposed to establishment diseases by omitting a fungicide seed treatment. Risks from seed and soil-borne diseases increase with later drilling because of colder and wetter soils.
3. Avoid ‘mauling’ seed in
Don’t maul seed into unsuitable seedbeds. You might feel a sense of relief that it has been planted, but the effects of planting in poor conditions can carry through not just to harvest, he says, but also into the following crop. Pre-emergence herbicides won’t work as well in poor seedbeds, resulting in bigger grass weed problems this season and increased weed seed return for the future. Seedbeds that are too wet to roll can also reduce seed to soil contact and crop germination.
4. Check variety growth habit
If you’d planned to drill earlier but been rained off, double check that your variety’s growth habit still suits the new drilling date, urges Mr Scott. It’s a complex area, he says, and you may need specific guidance. Our trials have shown big differences between the emergence and tillering of varieties as drilling shifts later. But not all varieties were equally affected. In an extreme case of December drilling, the best variety emerged 50% better than the worst.
5. Be aware of reduced vigour
As well as reduced tillering with later drilling, be aware of reduced crop vigour as crops are planted into colder, wetter soils, says Mr Scott, as well as the potential for lower vigour in seed carried over from last year. Lower vigour underlines the argument for planting into good seedbeds. But also consider an autumn micronutrient and bio-stimulant treatment to boost growth. It can improve root structure and help increase yield.
Nigel Scott is regional technical manager for agronomy firm ProCam.