Pest, disease and weed management

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Research outcomes: A comprehensive RD&E program that addresses existing and emerging pests, diseases and weeds, allowing sugarcane growers to manage their crops efficiently with minimal environmental impacts. An enhanced industry capacity to deal with incursions of exotic pests, diseases and weeds.

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1999 - 199912000 - 20024

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Author: search.filters.author.Allsopp, PGSubject: search.filters.subject.Canegrubs

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    Methods for accurate identification of canegrubs : SRDC final report BS97S
    (BSES, 1999) Allsopp, PG; Miller, LJ
    The objectives of the project were; determine morphological characters for accurate identifica6tion of larvae and adults of all species of canegrubs; validate the usefulness of morphological characters through DNA analysis; produce written and computer-based keys to enable extension staff and growers to accurately identify larvae and adults of canegrubs.
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    Effect of farming practices on canegrub incidence : SRDC final report project BSS166
    (BSES, 2002) Allsopp, PG; Sallam, MN; Dall, DJ
    The impact of farming practices on numbers of Childers canegrubs was determined in southern Queensland by a survey of 441 field-year combinations that related practices to the numbers of second- and third-instar larvae in those fields, and by a field experiment that tested combinations of insecticide application, cultivation practices and crop-residue retention on numbers of larvae and associated entomopathogens. There were significant differences in levels of infestation among years, soil types, crop ages, cultivars grown, insecticide-use strategies, crop-replacement strategies, intensity and frequency of tillage during crop replacement, and irrigation strategies. In the field trial, numbers of third-instar larvae declined as the larvae aged, probably through infection by the fungus Metarhizium anisopliae and the protozoan Adelina sp. Application at planting of the controlled-release insecticide suSCon? Blue had an immediate effect on the number of larvae carried over from the previous crop cycle and this effect continued into the second-ratoon crop. The insecticide application increased cane and sugar yields, particularly in the first-ratoon crop. More intensive preplanting tillage initially reduced numbers of larvae, but the effect did not continue into the ratoon crops. Management of crop residues had no consistent impact on numbers of larvae, but cane yields were higher and sugar content lower in the second-ratoon crop when residues were retained, and led to higher sugar yields where suSCon? Blue had been applied. In general, long breaks between successive sugarcane crops, coupled with intensive tillage in that break and application of controlled-release insecticide, will reduce subsequent populations of larvae. The alternative strategy of herbicide destruction of the previous crop, long fallow with minimum tillage, replanting without controlled-release insecticide and prudent use of transient insecticides in heavily infested ratoon crops will also minimise numbers and may allow better survival of entomopathogens. These strategies are integrated into management practices attractive to growers and have been extended within the Southern GrubPlan format.
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    Determining the biology of rhopaea canegrub in the New South Wales sugar industry : SRDC final report BSS201
    (BSES, 2002) McLennan, AJ; McGuire, PJ; Allsopp, PG; Zalucki, MP
    Rhopaea canegrub (Rhopaea magnicornis Blackburn) is the major insect pest of the New South Wales sugar industry with about 25% of Condong farms affected. Rhopaea has also been reported as a pest in the Broadwater and Nambour canegrowing areas. At the time this project commenced little was known about the ecology and population dynamics of the pest and no commercially viable control measures existed.Contrary to previous beliefs, some female beetles were observed to fly prior to mating. However, female beetles were also observed that emerged and did not fly, but mated on the soil surface before burrowing back into the soil where they laid their eggs. It is not yet known which behaviour is the most common. The average egg batch was found to be 21.3 eggs.The distribution of the life stages of rhopaea canegrubs was determined using both naturally occurring populations at three sites and an introduced population at a fourth site. First and second instars are shallow feeders; they were found at an average depth of about 10 cm. The third-instar rhopaea larvae not only move deeper into the soil (average depth about 15 cm) but also become more focused around the sugarcane stool and row centre. Finally, as pupation approaches, rhopaea grubs again move up in the soil profile, where they were found to pupate at an average depth of only 6.5 cm below the soil surface. Rhopaea is a comparatively shallow-living grub in contrast to some other canegrub species.Green cane trash blanketing was tested on six farms and ?stool rolling? on five farms. Neither practice was shown to be effective but this may be due to the relatively low pest populations that prevailed during the three years of field work.Fallowing as a control measure was tested with both naturally occurring populations and in a replicated trial where plots were seeded with 20 second instar larvae. A grass fallow was found to increase pest numbers in subsequent crops compared to replanting. In the replicated experiment, all fallow treatments reduced grub numbers by similar amounts four months after the larvae were introduced.Field counts made after land preparation for replanting showed that cultivation can reduce pest numbers by close to 100%. However, such large decreases may also disrupt the disease cycle which is essential in suppressing pest numbers.Disease studies showed that rhopaea is infected by a different species of Metarhizium fungus (M. flavoviride) than other canegrub species which are infected by M. anisopliae. The fungus affects all stages (egg-adult) of the pest so that the ?window of control? is very wide. Some field observations showed over 50% of a female?s eggs could be killed by metarhizium infections. Beauveria bassiana was another prominent fungal disease identified in the population. This fungus has only been rarely observed in other more northern canegrub species. Both fungi have potential as biological control agents.Other diseases found include milky disease (Paenibacillus popilliae), three minor fungal diseases and one incidence of a rare microsporidian disease (Nosema sp.).
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    Plant resistance to canegrubs : SRDC final report BSS132
    (BSES, 2002) Allsopp, PG; Cox, MC; Nutt, KA
    The project sought to determine the range and types of resistances to feeding by canegrubs in sugarcane clones and their wild relatives. Resistance was tested in both pot trials and field trials and the importance of several biochemical factors in this resistance was investigated.Field and pot trials showed that a range of tolerance and antibiosis resistance mechanisms to canegrub feeding exists within the current sugarcane genome and close relatives. Tolerance effects were apparent in the growth of tops, roots and stubble. Antibiosis effects were apparent on grub survival and grub growth. Some of these tolerance effects are partially correlated with the general vigour of clones, but there are a number of clones that depart from the general relationships for tolerance and antibiosis. These clones would be especially important in any future program to increase the levels of resistance within the breeding gene pool.There was reasonable repeatability of pot-based tolerance levels between pot trials and with results derived from field trials. However, the type of canegrub and its underlying biology influenced the usefulness of field trials.Biochemical investigations showed no clear relationships between any factor and antibiosis phenotypes. However, there were indications that the type of cell-wall sugars may influence resistance to canegrubs. In addition, the data clearly indicated that the quantity and type of phenolic compounds in the roots change following feeding by canegrubs.
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    Canegrub resistant plants containing antimetabolic compounds : SRDC final report BSS163
    (BSES, 2000) Smith, GR; Nutt, KA; Allsopp, PG
    Transgenic sugarcane plants engineered to express either the potato proteinase inhibitor II or the snowdrop lectin gene show increased antibiosis to larvae of Antitrogus consanguineus in pot-based glasshouse trials.Canegrubs feeding on the transgenic line UP87, transformed with the potato gene, gained as little as 4.2% of the weight of canegrubs fed on untransformed control plants. Similarly, larvae feeding on the roots of transgenic line G87, transformed with the snowdrop gene, gained only 20.6% of the weight of grubs feeding on the non-transgenic control plants. Overall, 22% of the tested transgenic plant lines engineered with either the potato or the snowdrop constructs resulted in a statistically significant reduction in gain of weight by canegrubs feeding on roots. Weight gains of insects were compared to those of larvae feeding on the roots of either non-transgenic control plants, or non-transgenic plants regenerated after passage through the tissue culture system.Plants transformed with a proteinase inhibitor from an ornamental tobacco showed no statistical effect on the weight gain of the grubs. This result was unexpected, as the proteinase inhibitor from tobacco was predicted to be as effective as the PI from potato. Further analysis of the gene construct by sequencing established that the gene construct was faulty in contrast to the original restriction analysis that had indicated that the plasmid was correctly constructed. Protein could not be produced by the faulty construct, and this is reflected in the negligible effect on weight gain of the grubs. The plasmid was re-constructed and transformed into sugarcane. Plants containing this construct are being grown for testing.Having now established that canegrub resistance can be engineered into sugarcane, the next phase is to test the efficacy of these transgenes against other species of canegrub larvae and to further develop a commercial product.