Ground Cover Supplement : GC Supplement - Crop protection
GROUND COVER CROP PROTECTION 18 CHEMICAL CONTROL THE 2010 CHICKPEA season in the northern GRDC region was characterised by mild temperatures, long cloudy periods and frequent rainfall events -- conditions that favoured waterlogging, vegetative growth, poor pod set and disease. In the latter part of the season most crops succumbed to botrytis grey mould (BGM), other moulds and weathering. This raised concerns about the availability of quality planting seed for the 2011 season. Accordingly, a survey of chickpea seed harvested from the 2010 commercial crop was undertaken. Eighty seed lots were processed for germination, emergence and pathology. The pathology work showed most were mouldy and many were infected with Botrytis cinerea. As well as causing BGM, B. cinerea causes a seedling root rot that can reduce crop establishment to unproductive levels. From the 80 seed lots two were selected that, after grading, had botrytis and reasonable emergence -- an uncommon combination for the 2010 harvest. These were used in the 2011 fungicide seed-dressing trials. Previous GRDC-funded research at Tamworth had shown that thiram alone or thiram plus thiabendazole gave excellent control of seed-transmitted ascochyta, but efficacy on seed-transmitted botrytis on naturally infected chickpea seed was unknown. Botrytis chickpea seed treatment trials One seed lot came from Moree with 22 per cent of seed yielding B. cinerea and 72 per cent emergence; the other came from Edgeroi with four CHICKPEA SEED RESEARCH TO IMPROVE CROP ESTABLISHMENT Surveys of commercial 2011 chickpea crops confirmed the value of seed treatment and highlighted the importance of correct application By Kevin Moore, Paul Nash and Gail Chiplin per cent B. cinerea and 79 per cent emergence. These were used in three field trials in northern NSW (at Moree, Bellata and Breeza) conducted in collaboration with the Northern Grower Alliance (NGA) to compare the efficacy of seed dressings in controlling botrytis seedling root rot. Seed treatments were thiram alone, thiram plus thiabendazole, iprodione and an untreated control. Plots were two metres wide by 11.5m long, five rows at 32-centimetre spacing with four replicates. Sowing rates were adjusted to give 35 plants per square metre. A similar trial at Tamworth using only the Moree seed lot also included new chemistry. The trials showed clearly that seed treatment increased crop establishment and controlled botrytis seedling root rot (Figure 1). At the time of writing, only the Moree trial data had been analysed. In that trial, treating seed increased establishment almost four-fold with the Moree seed and by almost two-fold with Edgeroi seed. Treating seed also decreased the number of plants with botrytis by almost 20-fold, with all fungicides effectively controlling the disease. Surveys of commercial 2011 chickpea crops confirmed the value of seed treatment and highlighted the importance of correct application: crops planted with inadequately treated seed had higher levels of botrytis seedling root rot than those treated according to label instructions. □ GRDC Research Code DAN00143 More information: Kevin Moore, NSW Department of Primary Industries, 02 6763 1133, email@example.com; www.grdc.com.au/DAN00143 Moree agronomist Phil Davis inspects the Moree GRDC- funded chickpea botrytis seed treatment trial on 8 July 2011. The middle plot was sown with untreated seed harvested from a 2010 crop that had high levels of botrytis grey mould, 22 per cent of which yielded the Botrytis cinerea fungus. The plots (each with five rows) on either side were sown with the same seed but treated with a registered seed dressing. PHOTO: KEVIN MOORE Figure 1 Chickpea seedlings from the untreated plot with root rot starting at the seed. The Botrytis pathogen sporulated on the discoloured roots after a 24-hour incubation in a humid chamber.
GC Supplement - Mixed farming
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