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Using nanoparticles of metalloids and metallic oxides in plant disease suppression

Wade Elmer: Connecticut Agric Exp Station

<div>Micronutrients, such as B, Cu, Mn, Mo, and Zn, can activate enzymes to initiate defense mechanisms against plant diseases. Other elements like Ag, Ce, Si, and Ti can also affect plant health through a variety of mechanisms. When these elements are applied as nanoparticles (1-100 nm) (NP), they perform better than their larger bulked equivalents. Evidence of basipetal transport has allowed the possibility of using foliar applications of NP to affect root nutrition and response to disease. In separate studies, NP were sprayed at 500 µg/ml onto chrysanthemums, grapes, pumpkins, soybeans, and strawberries. Pumpkins sprayed weekly with either CuO NP, ZnO NP, or conventional fungicides had less powdery mildew than their Cu and Zn salts or untreated plants (<em>P</em> = 0.021), whereas Chardonnay grapes treated with NP of CuO had only slightly less powdery mildew than untreated plants (<em>P</em>= 0.080). There was a tendency for B NP to increase strawberry plants weights when inoculated with <em>Verticillium dahliae. </em> Both CuO NP and MnO NP increased chrysanthemum weights in soils infested with <em>Fusarium oxysporum</em> f. sp. <em>chrysanthemi</em> (<em>P</em> = 0.050). The disease ratings of soybeans sprayed with NP of Ag, B, Ce, Cu, Mn, Mo, Si, Ti, and Zn and grown in soil infested with <em>F. virguliforme</em> were 27, 8, and 10% lower with Ag, Cu, and Mn, respectively (<em>P</em> = 0.027), when compared to controls. Overall, NP of CuO and MnO may offer a novel approach to improve plant health across many crops.</div>