Wheat Ear Sprays for Disease and Mycotoxin Control
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Topic Sheet No. 58 Summer 2002 Wheat ear sprays for disease and mycotoxin control Fusarium ear blight losses due to diseases caused by Five main species of fungi are these fungi and the mycotoxins responsible for ear blight in the they produce.While F. avenaceum UK.While all can reduce yield and F. poae are rarely important, and/or quality, only the Fusarium they can produce mycotoxins that species produce mycotoxins are even more potent than NIV (Table 1). or DON. The prevalence of ear diseases HGCA is funding surveys of varies considerably with location Fusarium mycotoxins in UK grain and year. Incidence and severity and to date, risk of contamination have increased in recent years appears to be low. (Figure 1). Wet weather at EU legislation, which already sets flowering is critical for disease limits for some mycotoxins development. produced by storage fungi, is likely Action: Fusarium graminearum and to be extended to include F. culmorum produce several mycotoxins produced by Fusarium Avoid growing highly mycotoxins including species. Grain containing toxin susceptible varieties in areas above these levels could be with a history of ear disease. deoxynivalenol (DON) and nivalenol (NIV), which are difficult or impossible to sell. Prepare to spray immediately harmful if consumed by humans if the weather is wet at and animals. Fungicide testing and flowering. choice Use fungicide mixtures to Mycotoxin risk In three years of HGCA-funded help control toxin-producing experiments, susceptible winter and non-toxin producing fungi. Mycotoxin formation in grain depends upon the predominant wheat varieties were grown at Use mixtures of fungicides species, temperature and other three sites. Crops were sprayed for maximum effect against agronomic factors. at GS 32 and GS 39 with broad- toxin-producing species. spectrum fungicides to control In several countries, maize and foliar diseases. Spray as soon as possible after wheat crops have suffered serious infection (or not at all). Monitor crop lodging. Table 1. Fungi causing ear disease and their effects Have grain tested if mycotoxin Species UK status Mycotoxin producer contamination is suspected. F. culmorum Sometimes severe – can halve yields. yes Only recently arrived in the UK, so rarely F. graminearum yes important to date. Elsewhere can be severe. If you are unsure about any of the F. avenaceum Rarely important. yes suggested actions, or want them interpreted for your local conditions, F. poae Commonly found, but rarely important. yes consult a professional agronomist. Microdochium nivale Often most common species in the UK. no Wheat ear sprays for disease and mycotoxin control Figure 1. Incidence and severity of Fusarium ear blight, 1991-2001 Summary 70 14 60 12 Foliar diseases of wheat Incidence Severity 50 10 usually cause the most yield 40 8 loss and are the focus of 30 6 fungicide treatments. Ear (severity) (incidence) 20 4 diseases, by contrast, often % ears affected % ears affected % crops affected affected % crops 10 2 cause less yield loss but can 0 0 seriously reduce quality if 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 weather at flowering is wet. Source: DEFRA winter wheat disease survey Plots were inoculated with spores Toxin-producing species increased Ear sprays mainly keep of M. nivale, F. culmorum, as non-toxin producing species grains bright and clean but F. graminearum and F. avenaceum. were controlled. Thus mycotoxin could also help reduce Mist irrigation encouraged disease. levels increased. mycotoxin formation. Several fungicides were tested. Reduced doses of any fungicide Recent HGCA-funded R&D Yields, fungal species and controlled disease less effectively has shown that a correctly- mycotoxin levels were measured. and did not reduce toxin levels to timed triazole spray (alone Tebuconazole (Folicur) and the same extent as full dose. or mixed with a strobilurin) metconazole (Caramba) showed can reduce Fusarium ear good activity against toxin- Fungicide timing blight and mycotoxin accumulation in grain. producing species and reduced Correct timing was necessary for DON levels in grain. control. Sprays applied during Further information: An MBC fungicide (Derosal) was flowering were most effective. Dr Paul Nicholson, John Innes Centre Tel:01603 450616 effective in the year tested. Spraying more than three days While azoxystrobin (Amistar) before, or after, infection led to Ongoing projects 2067, 2452 controlled Microdochium nivale poorer control. At these timings, well, kresoxim-methyl + reduced doses led to complete Project Reports 207, 230 epoxiconazole (Landmark) was loss of control. less effective. However, Amistar Results from one site indicated did not control the Fusarium Topic sheets that crop lodging can increase are free species that produce mycotoxins. toxin levels in grain. In the absence of M. nivale, To join our To ensure control of all ear blight mailing list Amistar generally had little effect pathogens, a mixture of DMI and contact HGCA on disease or toxin levels.Where strobilurin fungicide should be Home-Grown Cereals Authority M. nivale levels were significant, used in preference to a single Amistar used alone often led to product. Strobilurins should not Research & Development an increase in mycotoxins. Caledonia House be used alone. 223 Pentonville Road London N1 9HY The Home-Grown Cereals Authority (HGCA) has provided funding for this project but has not conducted the Tel: 020 7520 3945 research or written this report.While the authors have worked on the best information available to them, neither the HGCA nor the authors shall in any event be liable for any loss, damage or injury howsoever suffered directly or Fax: 020 7520 3992 indirectly in relation to the report or the research on which it is based. e-mail: [email protected] Reference herein to trade names and proprietary products without stating that they are protected does not imply http//www.hgca.com they may be regarded as unprotected and thus free for general use. No endorsement of named products is intended, nor is any criticism implied of other alternative, but unnamed products..