The use of a selected isolate of Pochonia chlamydosporia var. chlamydosporia in a field trial against Meloidogyne javanica and its quantification using both microbiological and molecular techniques.
FRANCO C.; VINAGRE L.; CLARA I.; VIEIRA DOS SANTOS C.; ABRANTES I.; SANTOS S.; FERNANDES J.; NETO E.; RAMOS N.; KERRY B. & MAGAN, N.
The effect of soil inoculation with chlamydospores of the isolate Pc-MR of the fungus Pochonia chlamydosporia var. chlamydosporia mixed with sterilized sand was evaluated in a tomato crop grown in an unheated plastic tunnel house. The effect was compared with an untreated control, methyl bromide fumigated soil and with an application of the fungus after soil fumigation. The fungus was inoculated twice and its soil population was quantified before and after each inoculation. At the end of the cropping season, the abundance of the fungus in soil and on roots, the amount of egg parasitism and the nematode population (total eggs and juveniles and eggs/egg mass) were also determined. The isolate identification was confirmed using primers derived from the β-tubulin gene and ERIC fingerprinting. The fungus population steadily increased in soil with both inoculations achieving the highest level at the end of the crop (2.4 to 3.9 x 104 cfu/g of soil). No decrease in fungal abundance was noticed, even one month after inoculation. Apart from after the second inoculation, there were no significant differences (P<0.05) between soil or root populations of the fungus in fumigated and non-fumigated soil. The final root population ranged from 7 to 19 x 103 cfu/g of root. Egg parasitism ranged between 38 - 51% and numbers of viable eggs + juveniles decreased by 74% and the eggs/egg mass decreased by 64% when compared to the control. The parasitism levels and nematode population reductions demonstrate the potential of this isolate for use as a control measure in IPM programmes against Meloidogyne spp.
Integrated control of Fusarium Ear Blight in wheat
Marie Guingouain, Stephen Rossall
University of Nottingham, Plant Sciences Division, Sutton Bonington, Loughborough, LE12 5RD
Fusarium ear blight (FEB), caused by several Fusarium species, is a worldwide disease of wheat (Triticum aestivum L.) and other small grain cereals. This disease can greatly reduce grain yield and is of concern because of the potential accumulation of mycotoxins in the grain intended for human and animal consumption. Available and affordable control measures, such as resistant varieties, cultural practices and foliar fungicides, are only partially effective. Biological control is an additional strategy that may eventually play an important role in an integrative approach to FEB management of cereals. The most effective control of the disease is indeed likely to be through an integrated approach that may be achieved by the combined application of fungicides and biocontrol agents to wheat varieties with partial resistance. In this study, biological and chemical control strategies were evaluated independently on the susceptible wheat cultivar Charger. Bacteria were isolated from stem, leaf and head tissues of wheat grown in field, and screened for in vitro antifungal activity. Strains shown to antagonise growth of F. culmorum and F. graminearum were further tested in laboratory assays and identified. Three of those, Bacillus subtilis, B. licheniformis and Pseudomonas fluorescens, were selected for in planta assays on ears in controlled environment. Bacterial treatments, applied at full ear emergence prior to inoculation with a spore suspension of F. culmorum at mid-anthesis, all reduced FEB incidence and severity, as well as DON content in grain. Treatment with foliar fungicides remains the most effective tool for reducing FEB. Tebuconazole has been proven to be effective at controlling FEB. The commercially available formulation (Folicur) was used as a control to test the efficacy of a new micro-encapsulated formulation produced by Micap plc. In this new product (known as Micap), tebuconazole was encapsulated in a yeast cells. When applied at rate equivalent to 0.5 L ha-1, Micap greatly reduced visual symptoms, percentage of shrivelled grains, mycotoxin content in grain and increased thousand grain weight. Future work will focus on combining chemical and biological treatments in three different wheat varieties, identified in a Monsanto genotype screening programme: Charger (susceptible), Rialto (moderately susceptible) and Centrum (partially resistant).
The influence of spray heterogeneity on the dynamics of fungicide resistance
S.R. PARNELL1,2, C.A. GILLIGAN2 AND F. VAN DEN BOSCH1.
1Biomathematics Unit, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK, 2Epidemiology and Modelling Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
Empirical evidence illustrates that the coexistence of fungicide resistant and sensitive strains is possible over prolonged periods (Bierman et al. 2000; Chin et al. 2001). However, models of fungicide resistance often predict that the invasion of resistant strains leads to the eventual exclusion of sensitive strains (Chin 1987; Gubbins & Gilligan 1999). The factors influencing