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Technical annual report 2000-01



Technical annual report 2000-01


Dept. of Regional Development, Primary Industry, Fisheries and Resources technical annual report; Department of Regional Development, Primary Industry, Fisheries and Resources technical and annual report; Reports; PublicationNT; Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295




Made available via the Publications (Legal Deposit) Act 2004 (NT).






Agriculture -- Northern Territory -- Periodicals; Fisheries -- Northern Territory -- Periodicals

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Dept. of Primary Industry and Fisheries

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Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295



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Department of Primary Industry and Fisheries 12 Two chemical applications were carried out by helicopter to control the pest complex. High insect pressure and the need for control measures at critical times are important management considerations in irrigated maize in the Daly Basin. Table 1. 1999 variety performance Variety Plot Yield Yield t/ha* PAC 338 179.9 a 6.02 Pioneer 1196K 269.9 b 9.06 PAC 269 275.2 b 9.11 Pioneer 3394 289.4 b 9.67 Pioneer 3158 289.7 b 9.63 DK 689 294.5 bc 9.74 Pioneer 31M10 306.7 bc 10.24 Hycorn 75 307.8 bc 10.28 Pioneer 3237 333.6 c 10.86 Hycorn 90 Observation only Ob. only LSD (p<0.05) 42.41, p-value < 0.001, CV(%) 8.0 *Means with common letters are not significantly different. 2000 Results: On 28 April 2000, 11 varieties were planted at DDRF. Planting was carried out using a Nodet Gougis precision vacuum planter. Nitrogen, phosphorus, sulphur and trace elements were banded beneath and to one side of the seed furrow at the rate 100 kg/ha (9 kg N, 19 kg P, 10 kg S, 2.5 kg Zn and 2.5 kg Cu). The varieties were established at a mean population of 86,000 plants per hectare. Banding of fertiliser at planting eliminated early nutrient deficiency that was evident in the 1999 crop. Insect pressure was extremely high throughout the season. Insect control was carried out on five occasions. Dimethoate was applied three times between week three and week five to control leafhoppers, which transmit Wallaby Ear Virus. Armyworm, Helicoverpa spp. and GVB were present in high numbers at silking. Insecticide was aerially applied twice, once prior to silking and once during silking. Rogor and Lorsban were mixed and applied by helicopter to control of GVB and Helicoverpa spp. and armyworm during pollination and early grain fill. After spraying it was apparent that plants were not effectively pollinating. A large percentage of plants in all varieties produced partially pollinated ears. Stems distortion was also evident in most plants. Some plants also produced as many as five barren cobs. Prior to spraying, the crop appeared in excellent health with no apparent nutritional disorders or phytotoxicity symptoms. Days after spraying it was obvious that normal pollination was not occurring. Plants also exhibited bending of the nodes above the ear. It was initially assumed that the symptoms were caused by hormonal herbicide, possibly as a contaminant in the helicopter tanks. This was later discounted. At this point the cause of the poor pollination and stalk bending is unclear. It is uncertain whether the stalk bending is reducing yield or whether it is linked to incomplete pollination. Investigation is under way to determine the possible causes.