CROP PROTECTION
Fungicides Post–harvest ‘clean up’ in grapes The main driver of grape vine powdery mildew Erysiphe necator is the quantity of inoculum carried over from the past season. The aim of a post-harvest “clean up” is to stop the production of cleistothecia, so that the infection can’t overwinter. Good disease control can prevent cleistothecia production. However, it is generally produced in the late summer to early autumn period, post-veraison, when powdery mildew preventative practices historically have ceased.
Appl. Microbiol. Biotechnol. 30:415-421. Gadoury, D.M. and Pearson, R.C. 1990. Ascocarp dehiscence and ascospores discharge in Uncinula necator. Phytopathology 80:393-401 Gadoury, D.M., Pearson, R.C., Riegel, D.G., Seem, R.C, Becker, C.M. and Pscheidt, J.W. 1994 Reduction of powdery mildew and other diseases by over the trellis applications of lime sulphur to dormant grapevine. Plant Disease 78:83-87. Gadoury, D.M., Wakefield, L.M., Cadle-Davidson, L., Dry, I.B. and Seem, R.C. 2012. Effects of Prior Vegative Growth, Inoculum Density, Light, and Mating of Conidiation of Erysiphe necator. Phytopathology 102 65-72.
Developing cleistothecia The initiation of cleistothecia sees the asexual sporulation stop in powdery mildew colonies. Once initiated, cleistothecia start out white, turn yellow, brown then finally black and once there is necrosis of the anchoring hyphae they are considered mature. Erysiphe necator cleistothecia can contain up to 36 ascospores. Once detached, the fruiting bodies are dispersed by rain splash onto bark, trunk, leaf litter and soil. Ascospore survival is consistently higher in exfoliating bark. Excel Oil, Lime Sulphur and HML32 + Nordox eradicate the mycelium network on the leaf surface and kill the developing cleistothecia. They will not kill the matured cleistothecia, so eradication before they mature is essential for the management of inoculum. This improves the long-term control of powdery mildew.
Pre-spray
An autumn eradicant fungicide followed by a pre-flowering eradicant can be critical in the effectiveness of a season long preventative fungicide programme. “Action taken to eradicate cleistothecia can reduce significantly the incidence and severity of powdery mildew” – Gadoury et al. Article supplied by Farmlands Horticulture. References: Blaich, R.,Heintz, C. and Wind, R. 1989. Studies on conidial germination and initial growth of the grapevine powdery mildew Uncinula necator on artificial substrates.
7 days post 3.5% Lime Sulphur
Acrobat MZ690
Alaris
600G/KG MANCOZEB
700G/KG DITHIANON
90G/KG DIMETHOMORPH
• Benchmark protectant fungicide against black spot and glomerella in apples. • Excellent fruit finish characteristics. • Good persistence.
• A systemic and protectant fungicide for the control of downy mildew in onions, grapes, lettuces and early and late blight on potatoes. • Active at many stages of the disease development. • Preventative, curative and anti-sporulant activity. • Foliar penetrant, translaminar and local systemic properties. • Stem protection, tuber blight suppression.
5kg: 141538
10kg: 110135
Aliette WG
Alto 100 SL
800G/KG FOSETYL–ALUMINIUM
100G/L CYPROCONAZOLE
• A systemic fungicide for the control of phytophthora in ornamentals and nonbearing kiwifruit, avocados and citrus. • Attacks pathogens at multiple growth stages, for better overall disease control. • The systemic activity allows it to travel upwards and downwards throughout the plant, creating a complete barrier of protection while preventing wash-off. • Systemic fungicide that protects quality and yields for a better return on investment.
• Specialist DMI fungicide with early curative and preventative activity. • Systemic activity protects new growth. • Used on stonefruit, vegetable brassicas and turf. 5L: 107658
1kg: 104582
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Farmlands Horticulture PRODUCTGUIDE
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