Blackgrass raising its head

As winter cereals enter the finishing straight, there have been a few reports this week of blackgrass raising its head above the canopy. Ciaran Collins, Teagasc Crops Specialist, tells us more.

Worryingly some of these reports have come from farmers who previously did not have a blackgrass problem. The presence of blackgrass needs to be taken very seriously and all methods, including crop destruction, should be employed to eliminate all plants before seed is shed. A single plant can produce 1,000 seeds, but this can be as high as 6,000 seeds in the absence of competition.

Herbicide resistance is widespread, so relying on herbicides is not an option. Where the population is low, roguing is an option. However, a follow up will be required in a few weeks as all plants won’t be visible yet. If the population is high or there are bad patches in the field, it may not be practical to rogue, so in these cases crop destruction with glyphosate is the best option. Whole cropping may also be an option if a market exists.

Crops update

Recent dry weather has slowed the spread of disease, particularly in winter wheat where leaf three infection with septoria is common and leaf two has septoria in some situations. Fortunately the weather obliged allowing most growers apply fungicides at the correct timing of flag leaf fully emerged, so this will further add to disease control.

Spring barley is relatively disease free, expect for early-sown Planet, which continues to struggle with both net blotch and rhyncosporium. Late-sown crops are benefitting from the recent longer, warmer days and are starting to fill out and make up for lost time.

Similar to winter wheat, beans badly needed the current dry spell to slow the spread of chocolate spot. This has been a major issue in early-sown crops in the south. However, it is vital to keep the interval tight between fungicides and this should not exceed 21 days. This will result in three fungicides in some crops. Signum (max total dose 2.0kg/ha), Elatus Era 0.66L/ha (once) and Amistar are excellent options.

Teagasc Tillage Edge podcast

The Teagasc Tillage team provides regular updates on crop management in the weekly Tillage Edge podcast. You can access the podcast here.