Blackgrass has been identified on Irish farms where there was previously no problem with the weed, according to Teagasc.
Experts have warned that this is a worrying development and one which tillage farmers need to be alert to.
“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,” according to Teagasc tillage specialist Ciaran Collins.
He has warned that herbicide resistance to blackgrass is widespread and has also advised tillage farmers that “relying on herbicides is not an option, where the population is low, roguing is an option”.
Collins said: “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.”
Teagasc tillage specialist said that the rate of disease spread has slowed down in relation to cereal crops over recent days.
Collins added: “This is particularly the case 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.”
According to Collins, spring barley crops are also relatively relatively disease free.
The one exception is early-sown crops of 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,” said Collins.
He said similar to winter wheat, beans badly needed the current dry spell to slow the spread of chocolate spot, which has been a major issue in early-sown crops in the south.
“It is vital to keep the interval tight between fungicides and this should not exceed 21 days.
“This will result in the use of three fungicides in some crops,” Collins advised.
Options for tillage farmers include:
- Signum (max total dose 2.0kg/ha);
- Elatus Era 0.66L/ha (once);
- Amistar.
The weather outlook for the week ahead which will see a combination of dry sunny days and rising temperatures will ensure that growth rates within crops will be maximised.