Topic Sheet No. 87 Summer 2005

Controlling gout on Incidence and symptoms The spring generation lays eggs in Gout fly ( pumilionis) is late May and early June. Larvae becoming more common with feed under the leaf sheaf, causing a earlier sowing of winter cereals. groove of damaged tissue on The pest now occurs in most of stems and preventing normal ear England and Wales, but not emergence.This can often result in generally in Scotland. substantial yield loss. In some high risk areas control is so difficult There are two generations a year: that some farmers choose not to the autumn generation infests grow spring wheat. early-sown winter wheat and ; the spring one attacks late- Autumn generation sown winter and spring wheat as control and yield loss well as barley. are immune. To establish the effect of gout fly In late September, the autumn infestation on yield and optimum generation lays eggs on the upper treatment timings, HGCA-funded sides of leaves. Eggs hatch in 7-10 trials were conducted in days. Larvae crawl down into the Action: Oxfordshire and Suffolk on wheat shoot to feed and cause the shoot crops at high risk, eg sheltered to pucker and swell. Consider sowing seed treated areas, or near woodland. with an insecticide such as Attacked shoots die by the Early-sown (early Sept.) crops imidacloprid (Secur) to help following spring, but most infested were found to be most at risk. protect plants against lower crops can recover well as new levels of attack by gout fly. Later-sown crops (Oct. onwards) tillers replace those lost. were often free from pest attack. Avoid unnecessary autumn insecticide applications for gout fly control. This can Figure 1. % Plant infestation in spring after various insecticidal seed encourage predators and and spray treatments parasites which help to control 45 Sibutol the spring generation. 40 Sibutol Secur 35 If an autumn insecticide is 30 applied for BYDV control, time 25 the application to optimise BYDV vector control; yield 20 response from gout fly control 15 is unlikely. % Plant infestation 10 5 0 If you are unsure about any Untreated A B C A B C of the suggested actions, or Cypermethrin Tau-fluvalinate want them interpreted for your A – GS11-12 local conditions, consult B – 10 days after A a professional agronomist. C – 20 days after A Suffolk, 2002/03 Controlling gout fly on wheat

Imidacloprid (Secur) seed In very severe cases of gout fly Summary treatment gave partial control infestation an early nitrogen Gout fly causes very obvious only of gout fly at lower levels of application may encourage damage in early-sown winter infestation (under half plants compensatory tillering. cereals. HGCA-funded trials, infested) (Figure 1) but not at conducted by Velcourt with higher infestation levels (over half assistance from ADAS, plants infested). Spring generation investigated the need for, and control efficacy of, gout fly control. The timing of spray applications was vital with GS11 (first leaf Autumn infestations may increase Crops attacked by the autumn unfolded) to GS12 (2 leaves the risk of damage by the spring generation generally seem to unfolded) being optimal. Later generation – a much greater recover without significant yield applications were not effective. threat to yield. However, loss. An insecticide seed additional insecticide spray treatment against BYDV can Product choice was less treatments in the autumn aimed give incidental and partial important than spray application at gout fly may harm beneficial control of gout fly and may reduce the likely spring timing. Cypermethrin and gout fly predators and parasites. tau-fluvalinate (Mavrik) gave generation. BYDV aphid vector equivalent levels of control A balanced approach would be to control should remain greater (Figure 1). use a seed treatment to protect priority than gout fly control in against both gout fly and BYDV. the autumn. Despite high levels of gout fly in This would reduce autumn gout some trials (over 60% plants fly populations, minimise impact Further information: infested), no significant yield on beneficials and predators and Dr Rosie Bryson,Velcourt response was found due to gout reduce the threat posed by the [email protected] fly control. Yield responses were spring generation. Jon Oakley,ADAS found where the addition of an [email protected] imidacloprid (Secur) seed Any autumn insecticide should Project Report 372 treatment had controlled BYDV be used to control BYDV aphid in the same trial. vectors. Pest management in cereals and oilseed rape – a guide, HGCA Autumn insecticide treatments aimed specifically at gout fly will not generally result in a yield response. However, a seed Topic sheets treatment or insecticide spray are free targeted at aphid vectors of BYDV To join our will afford some gout fly control. mailing list contact HGCA

Home-Grown Cereals Authority

Research & Development Caledonia House 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.