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Symptoms and Control Methods of Pythium Root Rot in Tulips

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The disease can be caused by Pythium ultimum, Pythium irregulare, and Pythium intermedium, all of which are fungi belonging to the oomycetes. The pathogen overwinters in diseased bulbs, diseased roots, and soil, and often spreads with the movement of diseased soil. High soil temperature, delayed drainage after rain, and prolonged moisture retention make the disease more likely to occur. Symptoms: At the early stage of the disease, translucent water-soaked spots appear on the roots, and after expansion they cause browning of the vascular tissue, resulting in root rot. After the bulb is infected, gray spots appear around the base of the bulb with brown edges. In severe cases, the bulb becomes soft and rotted. Planting diseased bulbs

The disease can be caused by Pythium ultimum, Pythium irregulare, and Pythium intermedium, all of which are fungi belonging to the oomycetes. The pathogen overwinters in diseased bulbs, diseased roots, and soil, and often spreads with the movement of diseased soil. High soil temperature, delayed drainage after rain, and prolonged moisture retention make the disease more likely to occur.

Symptoms: At the early stage of the disease, translucent water-soaked spots appear on the roots, and after expansion they cause browning of the vascular tissue

and result in root rot. After the bulb is infected, gray spots appear around the base of the bulb with brown edges. In severe cases, the bulb becomes soft and rotted. Planting diseased bulbs results in no emergence of seedlings, or poor development after emergence, or even stunting.

Control Methods

(1) Crop rotation is recommended.

(2) Choose high, dry plots for planting tulips.

(3) In areas with severe disease, where the previous crop carried a large amount of pathogen, spray or drench with 66.5% Previcur AS at 500 times dilution or 30% hymexazol AS at 600-700 times dilution.

(4) At the early stage of the disease, spray with 80% Lüheng No. 2 wettable powder at 800 times dilution or 50% Genfuling wettable powder at 800 times dilution.

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