Last call for the spraying season
Published 28/06/2011 | 05:00
Another spraying season is almost complete. Where does the time go? It seems like such a short time ago that we were getting ready to start weed and disease control on this year's crops. Most crops, especially winter wheat and spring barley, will have received their final fungicide application at this stage. Disease pressure has been low this year and most crops are very clean, although there has been some movement of septoria in the last week.
If your winter wheat has not received its T3 application in the past two weeks, it should be applied now. The inclusion of a half rate strobilurin with 0.5-0.75 rate triazole is recommended. The higher rate of the triazole should be used if there is evidence of septoria moving in the crop.
Gleam, Prosaro, Folicur or Caramba are triazole products of choice. A half rate morpholine should be included if there is any signs of mildew present. A systemic aphicide should also be included. Most spring barley crops are clean. With the projected price for grain likely to be higher this harvest than this time last year the application of a late fungicide could be financially beneficial especially if the last spray was two or three weeks ago. A half rate strobilurin plus a half rate triazole is recommended.
Aphid numbers are high but if less than 50pc of the plants are infected after ear emergence, the application of an aphicide is not justified unless the forecast is for warm and settled weather.
At early flowering or a growth stage of 61, aphid numbers need to exceed five per ear or 30 aphids per flag leaf to justify action. Remember, your insecticide will also affect natural enemies such as ladybirds and hoverfly grubs.
Additional measures to boost grain protein in spring wheat might be considered. Late season foliar nitrogen is the most effective means to increase grain protein content. An application of 30-40kg/ha of nitrogen applied as foliar urea will increase the protein content by 0.5-1pc. This is generally applied at the milky ripe stage or growth stage 70-75. Alternatively apply 10-25L/ha of nitrogen in the form of HN2, available as N16 flex system. This can be applied with the T3 but be wary of spraying on warm sunny days to avoid scorch. The T3 on spring wheat is possibly the last fungicide to be applied and should consist of a robust triazole rate plus a half rate strobilurin with or without a mildewcide.
Desiccation of winter oilseed rape is the next step for this crop but is still a number of weeks away in most cases. If about half the seeds in a random sample of pods are turning brown the crop should be ready for desiccation within a few days.
Most pea and bean crops are at the end of flowering and are clean. If there is evidence of chocolate spot in beans, spray immediately with Amistar, Folicur or Signum. These will also control ascochyta.