Grain yield reductions in spring barley due to barley yellow dwarf virus and aphid feeding

peer-reviewedThe occurrence and control of barley yellow dwarf virus (BYDV) in spring barley was investigated, at Oak Park, in the periods 1990 to 1993 and 1996 to 2001. Barley was sown in March and April and treated with either organophosphorous or pyrethroid aphicide at various plant growth stages. The most common aphid encountered was Sitobion avenae and MAV the most common strain of BYDV. In untreated plots of March- and April-sown barley, 0.85% and 5.9%, respectively, of tillers had virus symptoms. Best control of symptoms, from a single aphicide in March- and April-sown crops, was a treatment at growth stage (g.s.) 14. This treatment contributed 77% of the reduction in symptoms recorded for multiple treatments in April-sown plots. The reduction in grain yield due to high, moderate and low BYDV infection in April-sown barley was 1.1 t/ha (20%), 0.65 t/ha (10%) and 0.36 t/ha (7%), respectively. In Marchsown barley, pyrethroid aphicide applied at g.s. 14 significantly improved grain yield by 0.26 t/ha (4%). In the season having the most severe BYDV outbreak, a pyrethroid aphicide at g.s. 14 was best in controlling yield loss. Pyrethroid aphicide gave better control of symptoms and better yields than organophosphorous aphicide. The estimated yield reductions in untreated April-sown barley due to feeding damage by Sitobion avenae was 0.71 t/ha and 0.83 t/ha (10.6% and 11.3%) in the two seasons in which this aphid was plentiful. In the three seasons in which Metopolophium dirhodum was recorded the estimated yield reductions were 0.32 t/ha, 0.48 t/ha and 0.43 t/ha (5.2%, 5.6% and 5.7%)

An evaluation of seed-pellet insecticides in a precision drilled crop of sugar beet

peer-reviewedThe control of soil pests of sugar beet by means of seed-pellet insecticides was investigated on each of two farms in Co. Wexford from 2000 to 2002. The farms on which trials were conducted differed each season. A number of seed-pellet insecticides were compared with the standard methiocarb seed treatment, methiocarb supplemented with the in-furrow applied granule insecticide carbo furan-isofenphos and with an untreated control. Imidacloprid, Montur and thiamethoxam significantly reduced onychiurid numbers around seedlings compared with the untreated control and significantly reduced pest damage to seedlings compared with the standard methiocarb treatment. Imidacloprid gave best control of pest biting of seedlings and was as effective as the in-furrow incorporated granule insecticide in preventing pest damage and plant mortality at sites having moderate onychiurid infestations. Montur, while less effective than imidacloprid in controlling pest bites on seedling roots, gave consistently good plant establishment. Thiamethoxam was less effective than imidacloprid in some trials at reducing plant damage and mortality. The retardation of seedling growth and establishment recorded for insecticidepropamocarb combinations relative to insecticide-hymexazol combinations in some field and glasshouse trials could be overcome by replacing propamocarb with hymexazol

An Investigation of Seed Treatments for the Control of Crow Damage to Newly-Sown Wheat

End of project reportSeed treatments for the control of crow damage to newly-sown winter and spring wheat were evaluated in field trials from 2004 to 2007. Treatments included six fungicides, three insecticides, a product marketed as a bird repellent and three possible repellents. Various rates of selected compounds were investigated. Winter wheat was sown in December and spring wheat in late-January to mid-February. Sowing depth was 2 to 4 cm while some selected treatments were also sown at 5 to 9 cm deep. Crow damage was assessed by recording plant density and grain yield. Severe damage by crows was recorded. The plant population for untreated spring wheat seed in 2004, 2005 and 2006 was reduced by 59%, 72% and 89%, respectively. The corresponding reductions caused by crows to winter wheat sown in December 2004, 2005 and 2006 was 97%, 89% and 96%. Best control of crow damage was provided by the fungicide Thiram. Increasing the rate of Thiram applied to seed improved the control of crow damage by increasing plant density in the range 42 to 70% and 36 to 57%, respectively, for spring and winter wheat when compared with untreated seed. Anchor, which contains the fungicides Thiram and Carboxin, also gave reasonably good control. The commonly used fungicide product panoctine gave poor control of crow damage. Other treatments investigated were ineffective in controlling damage. Increasing the sowing depth to more than 4.6 cm significantly reduced damage to both treated and untreated seed when compared with similar treatments sown less than this depth

Control of insect transmitted virus diseases in cereals and sugar beet.

End of Project ReportThe objective of this investigation was to determine if, in a mild autumn when aphid numbers were high, the recommended aphicide treatments derived from earlier trial results were adequate to control BYDV in autumn-sown barley. Investigations on spring barley at Oak Park, 1990-1993, showed Barley Yellow Dwarf Virus (BYDV) can cause reductions in grain yield of up to 1.4 t/ha. These studies indicated that the risk of infection increased with lateness of sowing date. They also suggested that control of the disease might best be obtained by applying an aphicide at the 4-leaf stage of growth. The objectives of this investigation were to determine the growth stage at which aphicide should be applied in order to obtain best control of BYDV and to compare the effectiveness of systemic and contact aphicides in controlling the disease.Aphid numbers, species and infectivity with virus yellows were monitored in 20 beet crops between May and July over the period 1990-1999. Monitoring was undertaken to provide growers with an aphid-spray warning in order to minimise the risk of virus yellows and to establish aphid-thresholds which if exceeded would necessitate the spraying of crops with insecticide.Teagasc acknowledges the support of Irish Sugar, Sugar Beet Levy Farmer Funds and Cereals Levy Farmer Fund

Ultra high speed image processing techniques

Packaging techniques for ultra high speed image processing were developed. These techniques involve the development of a signal feedthrough technique through LSI/VLSI sapphire substrates. This allows the stacking of LSI/VLSI circuit substrates in a 3 dimensional package with greatly reduced length of interconnecting lines between the LSI/VLSI circuits. The reduced parasitic capacitances results in higher LSI/VLSI computational speeds at significantly reduced power consumption levels

Lichens of six vernal pools in Acadia National Park, ME, USA

Whereas lichen-habitat relations have been well-documented globally, literature on lichens of vernal pools is scant. We surveyed six vernal pools at Acadia National Park on Mount Desert Island, Maine, USA for their lichen diversity. Sixty-seven species were identified, including seven species that are new reports for Acadia National Park: Fuscidea arboricola, Hypogymnia incurvoides, Lepraria finkii, Phaeographis inusta, Ropalospora viridis, Usnea flammea, and Violella fucata. Five species are considered uncommon or only locally common in New England: Everniastrum catawbiense, Hypogymnia krogiae, Pseudevernia cladonia, Usnea flammea, and Usnea merrillii. This work represents the first survey of lichens from vernal pools in Acadia National Park and strongly suggests that previous efforts at documenting species at the Park have underestimated its species diversity. More work should be conducted to determine whether a unique assemblage of lichens occurs in association with this unique habitat type

A study of cultivation and sowing systems for cereals.

End of Project ReportDue to the pressure on cereal margins growers are seeking ways of reducing their costs of production. Reduced cultivation may provide cheaper and faster crop establishment, but in the past has been subject to problems with (poor crop establishment) weeds and soil compaction. With modern cultivation and sowing technology and methodology it may be possible to overcome these difficulties. In addition reduced cultivation is considered to be more environmentally friendly and sustainable than the conventional plough-based system. With these considerations in mind it was decided to start an experiment in autumn 2000 to compare the conventional system (PL) with reduced cultivation (RC) for crop establishment, and to examine the effect of incorporating the straw into then soil or baling and removing it. The treatments were assessed on winter wheat, and winter and spring barley. The parameters assessed included – crop establishment, yield and quality effects on disease levels, invertebrate pests and beneficials (aphids, slugs, earthworms, beetles), and soil conditions. The work reported here was conducted on four trial sites at Oak Park, Carlow and Knockbeg, Co. Laois from 2000 to 2003. the objectives were to establish the efficacy of RC compared with PL and to its effects on the parameters outlined above. Plant establishment was lower after RC in most of the experiments. Winter wheat yields were good irrespective of the number of plants established and there were no significant differences between cultivation or straw disposal method. The relative yields of the PL and RC treatments in winter barley varied over the three years; in 2001 there was no difference, in 2002 PL yielded 1 t/ha more than RC, while in 2003 the PL area produced 2 t/ha extra. Spring barley yields were similar on the PL and RC treatments. Broadleaved weeds were not a problem on the PL or RC treatments but there were more annual grass weeds on the RC plots. This was particularly serious in the winter barley experiments where sterile brome (Bromus sterilis) had a big effect on yield by 2003. annual meadow grass (Poa annua) was a problem in both PL and RC areas if not controlled by timely herbicide application; this was particularly so on the headland areas in the spring barley field. Disease assessment on the winter wheat trail showed no significant differences in Take-all or Eyespot levels between cultivation or straw disposal methods, although Take-all levels tended to be lower on the RC plots. Soil strength as measured by cone penetrometer and shear vane was higher on the RC treatments. In the winter wheat there was no difference in slug numbers between any of the treatments. Leaf damage by slugs increased in RC relative to PL but not significantly, in 2003. No below ground slug damage was found. Earthworm numbers in the winter barley increased significantly on the RC treatment relative to the PL as the study progressed. Straw incorporation increased earthworm numbers on both PL and RC treatments. Allolobophora chlorotia was the most common species in 2004. In the winter wheat the RC and straw incorporation increased earthworm numbers. Cultivation method had a greater effect on ground beetle numbers than method of straw disposal. Large species (e.g. Pterostichies malanarius) were favoured by RC while smaller species (e.g. Bembidon species) were more numerous in the PL plots. Molecular studies on virus diseases, vectors and vector-predators are underway in progress. In the invertebrate pests and beneficials investigations the RC winter barley had 11% fewer aphids and 27% less BYDV than the PL. Incorporating straw reduced aphid numbers and virus incidence by 36% and 32% respectively; the comparable values for the PL + straw treatment were 15% and 15%. In the winter wheat there was less BYDV in the RC plots than the PL + less were the straw was incorporated than where the straw was removed. Aphid infestation of wheat ears was low in the three years of the experiment. The insecticide seed treatment imidacloprid significantly reduced aphid numbers and virus incidence in winter barley but was less effective than a single insecticide spray in controlling the disease. The seed treatment was more effective in controlling BYDV in RC than in the PL plots. Estimations of slug numbers in the winter barley showed that the dominant species was the grey field slug (Deroceras reticulatum). Slug numbers increased significantly on all treatments between 2001 and 2004. In November 2004, slugs were significantly more numerous in the RC treatments than in the PL areas. Leaf damage was proportional to slug populations, but the slugs did not damage the barely seed or reduce plant populations in continuous winter barley under RC. Root and stem diseases (Take-all and Eyespot) were not nay worse under RC than after PL. In fact there was a tendency towards lower disease levels on the RC areas and there was significantly less sharp eyespot on the RC treatment

Effects of Biosolids at Varying Rates on Earthworms ( Eisenia fetida

Land spreading is a major option internationally for the disposal/use of treated sewage sludge (biosolids), but effects of this practice on soil organisms are largely unknown. This study investigated the effects of biosolids on two soil invertebrate species, earthworms (Eisenia fetida) and Collembola (Folsomia candida), in laboratory tests. Five biosolids from different sewage works were assessed at rates equivalent to 0, 2, 5, 10, and 20 t ha−1. Biosolids applied at 2 and 5 t ha−1 did not cause mortality of adult earthworms but did at 10 and 20 t ha−1. At 5, 10 and 20 t ha−1, all biosolids had significantly fewer juvenile worms relative to controls. Increasing the rates from 2 to 10 t ha−1 did not impact on the number of adult Collembola, but at 20 t ha−1 there were significantly fewer adults. There were significantly fewer juvenile Collembola recorded for biosolids applied at the 2 t ha−1 when compared with controls, and also when biosolids were applied at 5, 10, and 20 t ha−1 relative to 2 t ha−1. Some significant difference between biosolids were observed, but generally, negative effects were not related to heavy metal concentrations in biosolids. It is recommended that possible detrimental mechanisms (e.g., ammonia production, lack of oxygen) be investigated in future work. It is concluded that biosolids, applied at legal, low rates (about 2 t ha−1) are unlikely to be detrimental to earthworms or adult Collembola but can be detrimental to Collembola reproduction