Assess maize carefully as slow maturity delays cut

While some crops have already been harvested, maize maturity has slowed up again in many areas following the cooler weather of last week, according to Grainseed technical manager Neil Groom.

Dry matters in the Farmers Weekly/Grainseed maize dry matter assessments have risen to a peak of 27.3% this week, with most samples bet-ween 22 and 25% dry matter (see table).

“In Dumfries SAC farm manager Hugh McClymount reports air frosts on low lying land throughout the county and neighbouring Cumbria. This has burnt off top leaves and affected plants along hedge backs,” explains Mr Groom.

Growers will need to strike a balance between what to do with frosted crops as plants often look worse than they are from the road. “Go well into the field and assess how much green leaf is left. When there is more than 50% leave the crop as sugars in the leaf will be converted to starch in the grain as the crop matures.”

It may be worth using an additive at harvest when the frosted leaf has mould growing on it to reduce spoilage at feedout, he adds.

MGA agronomist Simon Draper is also warning farmers to check crops thoroughly before deciding to harvest. “All too often the decision to cut is based on the dry matter of one or two cobs at the field edge. To be sure dry matters are right for cutting you should be sampling at least 10 cobs from one row, going right into the field to ensure you gain a cross section of the crop.”

Recent MGA workshops have seen groups of growers assessing dry matter in crops with cobs from the same field varying in dry matter by up to 10%, he says. “Gaining an average selection of cobs is the only way of getting a true dry matter reading for a crop.”

Mr Draper also urges caution on eye spot, with many areas of south west England heavily affected by the disease. “Where crops are affected they should be harvested while there is still some green leaf to go at. Leaving it too late will mean crops die off quickly, leaving little valuable material to be harvested. It may mean sacrificing dry matter, but that is likely to be the case on many units this autumn.”

And with dry matters remaining low Mr Groom says a late harvest will mean attention needs to be paid to field management after crops have been cut. “As soon as crops are clamped fields should be managed to prevent soil erosion and nutrient loss. Compaction could be a major issue this year as many crops won’t be harvested until mid-October, so sub soiling may be necessary, this will help rain soak in rather than running off.

“Where crops have been grown on sloping fields the top of the slope should be cultivated first to ensure any ensuing rain can’t build momentum as it heads down the slope,” he adds.

For those wanting to sow late winter forage crops, such as Italian ryegrass Mr Draper says accepting a lower dry matter maize silage may be best option. “Achieving more than 30% dry matter will be tricky this year, so harvesting at about 28% may be the best option.”

Maize harvesting

With maturity slowing and eye spot an issue for some areas, achieving high dry matter maize silages could be tricky this autum.

Maize issues
  • Low DM increases
  • Watch for eye spot
  • High DM difficult
  • Beware run-off after harvest

Farmers weekly/grainseed maize dry matters
Site Drill date Ht above sea level (m) Crop dry matter
14 September
Petworth, Sussex 20 April  50  27.3 -0.5
Harleston, Norfolk  23 April 30 24.0 +1.6
Crediton, Devon  17 April 118 22.5 +1.4
Ticknall, Derbyshire 12 April 67 24.9 +3.2
Poyerston, Pembroke * 2 May 20 23.6 +0.3
Leyburn, N. Yorks * 23 April 140 24.9 +1.3
SAC, Dumfries, Scotland* 23 April 45  22.0 +0.4

* Variety Nancis, all other sites are Agreement

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