13th April 2002
News
13th April 2002
News |
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 CROPS News | Husbandry | Features| Crop Protection Some crops are bombing along By Andy Doyle Crops are bombing along in south Tipp. Winter barley is at second last leaf emerging and winter wheat is a strong GS 32 with the third last leaf emerging. But rhyncho is on a roll and septoria is thriving in the wheat variety Claire. On Monday Glanbia held a field walk on John Byrne's farm south of Clonmel. These were among the most advanced crops I'd seen so far this year, but the appearance from a distance would not suggest this. All the crops we had time to visit that evening were early sown, mid to late September, and this was telling in growth stage. Regina barley We visited two crops of winter barley that were marginally different. One seemed to have more leaf area but it also had more rhyncho. The more advanced of the two crops was sown three days earlier. Seeding rate was similar but the more advanced crop had been treated with Latitude. It was also located slightly lower on a hill but still was an adjacent crop. The less advanced crop seemed to have less rhyncho at this point. Even the more advanced crop seemed soft to walk through but then winter barely has the ability to harden its stems during stem extension. But there is always the fear that 'soft' stays 'soft'. There was little doubt that the big concern was rhyncho. Over the past few days rhyncho had moved from relatively low levels to appear on the third last leaf, second from the top currently. And it wasn't just present - there was a lot coming through. Few mature lesions as yet but looking through the leaf into the light revealed all the watermarks associated with the developing lesions. The most advanced tillers had the flag leaf just peeping but most had the second last leaf unfolding. An odd stem had the flag leaf fully unfolded but these were most likely volunteers carried over from the stubble. Some of these had rhyncho right up on the second last leaf, which brought it high up the canopy to infect adjoining plants. Regime There is little doubt that the first fungicide, yet to be applied, must lean heavily on rhyncho. But this cannot afford to ignore eyespot. Either way the crop is confined to a two spray fungicide regime, one immediately and one in three weeks, which will take this crop through to mid-June for a July 10 harvest. The crop had received 117 kgN/ha (94 units) to date - 45 kgN/ha in early March and 72kg on March 23. The crops dropped back in colour recently but this may be more a result of the night frosts rather than the crop running out of nitrogen. The aim is to apply more nitrogen this week bringing the total applied up to around 165 kgN/ha (132 units). This may be delayed a bit, if the crop picks up in colour, so as to try and keep grain fill going a bit longer. Winter wheat This was a crop of Claire drilled on September 26 at 157 kg/ha (10 st/ac). A continuous wheat field but Latitude was still used to see if it might contribute to yield. While the seed rate was high for a Latitude-treated crop sown in September, the crop did not appear excessively dense. So far 140 kgN/ha (109 units) has been applied with 50kg initially in early March as 10:10:20. The plan is for more nitrogen soon. However, following a discussion on nitrogen fertilization of winter wheat the option of nitrogen post-flag leaf emergence is being considered. There may not be enough nitrogen on this crop to date so there could be two more splits to be applied ö about 35kg followed later by 50kg. In wheat crops after beet this amount would probably suffice for the moment with a single dose applied sometime post flagleaf. The crop looked quite short and squat following application of Meteor. Despite this it was a definite GS 32 (second node) with the third last leaf emerging. No sign of an extra leaf at this point despite the early drilling. Maybe the autumn density helped prevent this from happening. Being Claire the first search was for mildew. Perhaps surprisingly there was none present. This particular area would not be renowned for mildew but septoria was taking up the slack. For this variety there was an enormous amount of septoria tritici present, enough to be an ongoing threat. This is certainly a case for a strong eradicant like Opus or Flamenco mixes. The next concern was eyespot. On first observation this was not very evident but on closer examination 40 per cent of the main stems and stronger tillers has eyespot lesions. These were all relatively fresh and had not penetrated the stem so far. While stem infection might not take place the level of infection would necessitate some action. The presence of a strobilurin in the first spray will be an important inclusion. Depending on the triazole being used - Allegro, Twist, Modem or Acanto would make useful strobilurin partners at T1. For T2, Opera would be the best choice if the septoria continues to threaten. Spring cereals While we did not visit any spring cereal crops Teagasc adviser, Jarleth Harte, said all crops will need a BYDV spray. Because aphid numbers are low Jarleth suggested this could be combined with the herbicide on early drilled crops at about the 4-5 leaf stage this year. Jarleth said the continuous use of Ally plus CMPP had led to problems developing. Black bindweed had become a considerable problem and he suggested that growers should consider other herbicide options like Cameo plus a wetter when the weeds are still small. Nature responds to man's intervention and it is important for growers to alter husbandry to prevent new problems developing. |
Copyright © : The Irish Farmers Journal 2002 |
