![]() Copper-Count-N at 1 quart/100 gal water.C-O-C-S WDG at 2 to 3.9 lb/100 gal water.Astun at 10 to 17 fl oz/100 gal water.Limit the use of any one group during crop production. Tank-mix and/or alternate products with different modes of action to prevent the buildup of resistant fungi. Moving the plant to a more open location that allows for better air circulation may help.Ĭhemical control Use as foliar sprays, but concentrate on cultural controls.Avoid overhead irrigation or any practice that keeps plants wet for extended periods of time.Removing the top few layers of soil around plants may reduce risk by removing sclerotia.Do not use mulch in spring when plants are emerging.Remove and destroy diseased plant parts both during the season (especially spent flowers) and more generally at the end of the season.Late blight also produces sclerotia at the base of stalks, but they are much larger and flatter.Ĭultural control Reducing plant wetness is the most important tactic for limiting disease development. This is in contrast to the dense, tightly compressed growth of early blight. The fungus produces a sparse mycelial growth that stands far out from infected tissues. Late blight-similar, but it usually affects only flowers that open late. Later in the year, small, shiny black, slightly loaf-shaped sclerotia form near the base of infected stalks, just under the epidermis. Leaf spots may develop when infected petals fall on foliage. Stems develop a concentric brown and tan zoned appearance. ![]() Blackened buds or flowers may continue to rot down the stem. Buds may turn black before they develop or may be blasted when half open. A dense, velvety gray fungal growth usually covers the rotting portions. Shoots may appear to suddenly wilt and fall over. Symptoms Early blight-young shoots can rot as they come through the ground or at the base when only a few inches high. There is a wide range of susceptibility in various cultivars of peony. They will form black, overwintering structures called sclerotia, which can survive in plant debris left over or mulched around the bases of plants. These tissues, especially petals, can be the source of the fungus when they fall onto healthy leaves. ![]() The fungi can colonize peony petals and other plant tissues. Conidia enter the host through natural openings, directly, or through wounds. Spores can be blown by wind, splashed by rain, or carried on tools. Subsequent spores are produced on infected plant material. The first conidia arise from sclerotia that have overwintered on the surface of decayed peony foliage. These fungi are favored by wet, rainy conditions that result in free moisture on plant surfaces. cinerea could be from any of its over 250 hosts. paeoniae will be from previous or nearby peony crops while that of B. pseudocinerea that is resistant to fenheximide. Additional species have been found in the PNW including B. Cause The fungi Botrytis paeoniae (sometimes called early blight or bud blast) and B. ![]()
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