Crop Watch: Rain makes weed control a priority

Almost all areas were blessed with rain last week, giving crops a welcome boost and turning the attentions of Farmers Weekly’s Crop Watch reporters to weed control and crop management.

Patrick Stephenson, Yorkshire, said oilseed rape crops were “romping on” and the most forward would receive a fungicide with growth regulatory properties. Weed control had been good despite dry conditions and fields with a known blackgrass issue would be targeted with propyzamide or carbetabmide when soil temperatures dropped, he added.

But pre-emergence weed control in cereals had been a “mixed bag” with some programmes abandoned due to the dry weather, he noted. “Recent rain will no doubt lead to a large weed flush and a subsequent re-adjustment to our strategy.”

Rainfall had been less significant in the east, said. “It has softened soils, but the wind and sun has dried a lot of it up.”

Patchy rape crops were being monitored to see if rain had triggered germination and significant leaf miner damage was evident, he said. “But I have found pupa, so hopefully the worst is over.”

In the south, crops were showing signs of drought stress, but thanks to the rain should grow quickly and even out, said Agrovista agronomist, Swaran Bachoo, Hampshire.

All of his winter rape had received a graminicide to control volunteer cereals and he warned growers with untreated crops to apply immediately. “Following the rain, volunteers will grow rapidly and compete vigorously with the small rape plants – use robust herbicide rates as these chemicals are notoriously slow to act and large plants will need higher rates.”

Some winter wheat and winter barley had received a pre-emergence herbicide and the remaining would be treated this week. Oilseed rape crops had remained phoma free, but he advised growers to keep a close eye on the crop. “Be vigilant and look for the typical creamy white leaf spots with black dots and be prepared to spray.”

Winter barley drilling was almost completed in Shropshire, said AICC agronomist Bryce Rham, and forward crops were at GS21. “All are a bit tender and would like some cold nights to harden them off before we start spraying.”

Forward oilseed rape crops were at six to eight true leaves while September-drilled crops were still at cotyledon. However, they would probably grow away following the rain, he said. Phoma was starting to appear, although it hadn’t reached threshold, and leaf miner damage was visible, he added.

“Crystal (pendimethalin + flufenacet)/Graduate (flurtamone + diflufenican) has let me down for the first time in winter wheat following oilseed rape. “Volunteer rape has got through it and will need an over-spray to remove it.”

Click below for the full report from each region

Crop Watch East – Brian Ross

Crop Watch West – Bryce Rham

Crop Watch South – Swaran Bachoo

Crop Watch North – Patrick Stevenson

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