PT - JOURNAL ARTICLE AU - Percival, Glynn C. AU - Keary, Ian P. AU - Marshall, Kelly TI - The Use of Film-Forming Polymers to Control <em>Guignardia</em> Leaf Blotch and Powdery Mildew on <em>Aesculus hippocastanum</em> L. and <em>Quercus robur</em> L. AID - 10.48044/jauf.2006.013 DP - 2006 May 01 TA - Arboriculture &amp; Urban Forestry (AUF) PG - 100--107 VI - 32 IP - 3 4099 - http://auf.isa-arbor.com/content/32/3/100.short 4100 - http://auf.isa-arbor.com/content/32/3/100.full AB - The effects of four commercially available film-forming polymers (Bond, Designer, Spray Gard, Nu-Film-P) on disease severity of powdery mildew (Microsphaera alphitoides Griffon and Maubl.) on English oak (Quercus robur L.) and Guignardia leaf blotch (Guignardia aesculi (Peck) Stewart) on horsechestnut (Aesculus hippocastanum L.) were examined in a field experiment. In addition, a comparative evaluation of the fungicide penconazole, commercially used for powdery mildew control, was conducted. Effects on tree vitality were also assessed by measuring leaf chlorophyll fluorescence and chlorophyll concentrations. Irrespective of tree species, Nu-Film-P and Spray Gard did not significantly influence disease severity of powdery mildew and Guignardia leaf blotch. Likewise, no significant effects of these two film-forming polymers on chlorophyll fluorescence and chlorophyll content were recorded. Reduction in disease severity following spray applications of the film-forming polymers Bond and Designer was statistically comparable with penconazole. None of the film-forming polymers and fungicide evaluated was phytotoxic to the test trees. Results suggest that application of an appropriate film-forming polymer may provide a useful addition to existing methods of plant disease control.