Some rain has appeared at last within the past couple of weeks – enough to potentially encourage disease development. Any crops with reasonable yield potential are being topped up with a T3 treatment to extend the period of protection and try to maximise green leaf retention and increase grain fill.
In milling wheats, the T3 is also targeted at fusarium as the dry spring has been conducive to F culmorum development which has been climbing up the leaf layers as confirmed by monitoring sites. The risk of subsequent disease development on the ear is increased by wet weather. Also yellow rust is likely to become more active with increased leaf wetness so susceptible varieties will also be candidates for a T3 top-up fungicide.
Grassweed control has generally been good where stale seed-beds and pre-emergence residuals were successfully utilised in the autumn. Early autumn Atlantis (iodosulfuron + mesosulfuron) treatments worked well, but conditions for spring applications were not always ideal.
Again we have seen the benefit of residual stacking in commercial crops and in trials where Atlantis resistance issues are confirmed or suspected. Any surviving blackgrass this year should be noted and ripe seed samples collected for resistance testing – without this information it is impossible to formulate accurate control strategies.
Aphids have been evident in many cereal crops as well as cereal leaf beetle. Spring barley is particularly affected with leaf beetle larvae scraping away “windows” of green leaf tissue. In crops which are under significant stress it seems worth trying to reduce pressure from these pests with a foliar insecticide added to the T2 fungicide + foliar nutrient.
Pea aphid and black bean aphid have been sprayed with pirimicarb. A pyrethroid has been added in beans where bruchid beetle are an issue with follow up treatments 7-10 days later. Disease levels so far have generally been low with some downy mildew development in beans.
Recent rainfall is likely to encourage disease and require follow up fungicides based on triazole or triazole + chlorothalonil. After last year’s experience of silver Y moth and dry conditions, this year’s beet crops will be monitored for caterpillar damage over the coming weeks.