| Now a new disease is commonly found in Northeast China Region, the rate of the diseased plant is above80%in serious plot, if the maize was infected before six leaf stage, there would have no ear and reap nothing. The typical symptom of diseased plant is dwarf, yellow stripe is found on the upper blade of pathogenic site, sometimes tillering can also be found, the disease is temporarily named maize dwarf disease, the aetiological agent is not entirely clear, but the preliminary study found that the key factor was parasitic nematodes in the soil, they could infect maize during the progress of seed germination and resulted in maize dwarf disease. So according to the analysis, an effective means to control the disease is to use maize seeds with seed coating that have nematocidal activity.Fosthiazate is an novel non fumigation of organophosphorus nematicide, which is developed by Japan ishihara company, it has remarkable systematic activity and can conduct upward in plants. Fosthiazate belongs to medium toxic compound, it has an excellent control effect on nematodes both in soil and plants and the control efficiency is stable, it is also safe and pollution-free to human and environment. There aren’t relevant reports and products about fosthiazate seed coating at home and abroad, because fosthiazate has chemistry stress effect on seeds, can lower rate of emergence and influence seedling growth, so it can’t be used as seed coating formulation directly. If fosthiazate is used as seed coating formulation to control maize dwarf disease, slow-released seed coating formulation must be developed in order to improve the security of foshtiazate and prolong persistence and efficiency by reducing direct contact with maize seeds and seedlingThe contents of this paper is mainly divided into three parts, the first part is the preparation of15%fosthiazate CF; the second part is contrasting the coating effects on physiological and biochemical indexes for maize emergence between15%fosthiazate seed coating formulation and15%fosthiazate CF; the third part is the control effect of15%fosthiazate CF on maize dwarf in the field.(1)The preparation of15%fosthiazate CF:fosthiazate as capsule core, melamine formaldehyde resin as wall material, it was prepared by in-situ polymerization of fosthiazate/melamine formaldehyde resin microcapsule. Firstly, the prepolymer solution was synthesized by condensation polymerization using melamine and formaldehyde as raw materials under the condition of alkaline; secondly, a stable O/W emulsion was gotten using1601as emulsifier, SMA as dispersant, preparation of (fosthiazate and xylene)/water O/W emulsions; Thirdly, fosthiazate microcapsules were prepared successfully by in-situ polymerization while using5wt%HC1solution as curing agent and adding NH4CI as hardener after the completion of reaction, Finally,15%fosthiazate CF was got by adjusting pH to6.9with5wt%NaOH solution, adding NDSF as film-former,xanthan gum as thickener,ethylene glycol as antifreeze. The particle size, encapsulation rate and thermal storage stability were investigated, the meidium diameter was5.00μm, encapsulation rate was89.8%,under the conditon of heat storage, the decompositon rate was10.19%.(2) The coating effects on physiological and biochemical indexes of seedling and sprout of maize between15%fosthiazate seed coating formulation and15%fosthiazate CF were contrasted.15%fosthiazate CF improved germination rate, alleviated inhibiting effect of plant height, fresh weight of aerial part, root length, fresh weight of underground part, and improved soluble protein content, root respiration rate and CAT, POD activity, postponed the reduction of chlorophyll a, b content, SOD activity and inhibited the increase of malondialdehyde content. The stress resistance of maize was greatly improved, phytotoxicity was relieved and the security of seedling was also improved.(3) The control effect of15%fosthiazate CF on maize dwarf disease were73.68%and100%respectively in23day and37day after sowing, so it has great fast-acting property and persistent effect. |
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