July is the ideal time for tillage farmers in Ireland to assess the presence of grass weeds in their fields. This assessment is crucial for implementing an integrated pest management (IPM) control plan. Farmers should identify the types of weeds present and record their locations in specific fields. The task becomes easier when grass weeds have headed out, but if there is any uncertainty, agronomists can provide assistance. If the population of weeds is small, hand roguing can be done. Alternatively, if seeds have not yet been set in the head, larger areas can be desiccated. In cases where there is a suspicion of herbicide resistance, farmers should contact their local Teagasc advisor to arrange testing.
The results of herbicide resistance testing conducted by Teagasc using samples submitted by Irish tillage farmers in 2022 have raised concerns. More than 70% of the black grass or Italian ryegrass samples tested were found to be resistant to both ACCase and ALS herbicides. Additionally, it was discovered that poppies were resistant to ALS and/or hormone type (2,4-D) herbicides. Farmers who suspect the presence of herbicide resistance in grass or broadleaved weeds, specifically black grass, Italian ryegrass, or poppy, should make use of the free testing service offered by Teagasc. This will enable them to identify an effective herbicide program to be used in conjunction with integrated weed management strategies.
Proper sample collection is crucial for successful testing. The following procedures should be followed for grass weeds: cut off the mature seed heads and place them directly into a paper envelope or bag. Gently rub or shake the heads inside the envelope, ensuring this is done in a secure area away from the field to prevent seed escape. Seeds should be collected on dry days, but if they are damp, they should be allowed to dry away from sunlight before threshing. For broad-leaved weeds, farmers should cut off the mature heads directly into a paper envelope or bag and keep the envelope open for a couple of days to allow further drying. Another method is to cover the top of the weed plant with “party bags” so that the seeds fall into the bag instead of onto the soil, making the collection process easier. Farmers should collect seeds when they are ripe and easily fall from their seed heads, as mature seeds germinate rapidly. Seeds collected too early or from intact heads will be unripe or immature and will not germinate.
In conclusion, July presents an opportune time for tillage farmers to assess the presence of grass weeds in their fields. By accurately identifying the types and locations of these weeds, farmers can develop an integrated pest management control plan. The results of herbicide resistance testing conducted by Teagasc have highlighted the prevalence of resistance in black grass, Italian ryegrass, and poppy samples. Farmers who suspect herbicide resistance should avail of the free testing service provided by Teagasc to determine an effective herbicide program. Proper sample collection techniques are crucial for successful testing, and farmers should follow the recommended procedures for grass and broad-leaved weeds.