at the bottom of the bulb. difenoconazole Browning and rotting of roots and tebuconazole + appearance of white-pink. trifloxystrobin Damping off fungi, Soil-borne pathogens that infect Use treated seeds. No treatment threshold Pythium spp, seedlings, leading to red-brown Crop rotation. and Rhizoctonia spp lesions on stems and roots, causing Avoid wet soils. Use seed treated with mancozeb, them to wilt and die. Favor good drainage and good soil aeration. thiram Water only when soil is dry. Constitute a major constraint for difenoconazole onion production during the rainy tebuconazole + season. trifloxystrobin Pink Root, Soil-borne pathogen that infects Use resistant varieties (resistance may be No treatment threshold Phoma terrestris, seedlings, leading to pink lesions overcome if soil temperatures of 28°C or higher on stems and roots, causing them occur. No fungicides are recommended. to wilt and die. Pink and red roots Schedule planting so that the bulk of the root and dried out. Infected roots first growth occurs prior to reaching soil turn light pink, then darken temperatures that favor disease development through red and purple, shrivel, (24-28[C) turn black, and die. Eventually Rotate out of infested onion fields for 4-6 years. stunted plants. Remove weeds and plant residues. Plant in friable, well-drained soils. Major disease constraint for onion Do soil solarization. production. Ensure good soil tilth and fertility. Avoid planting onions after cereals. Downy mildew, Downy mildew infects onions and Plastic mulch covering to avoid plant contact No treatment threshold found. Peronospora garlic, via air-borne spores. The with soil and minimize weeds that enhance destructor first symptom noticed in the field microclimate conditions favorable to disease metalaxyl is often large circular clumps of dispersion. mancozeb infected plants. Heat treatment of bulbs at 35 to 40 °C for 4 to copper oxychloride A fine, gray-white to purple 8h reduces the disease significantly. growth appears on older leaves, Eliminate crop residues, plant during dry becoming pale green-blue and season, avoid irrigation during heat of the day. finally yellow before stem Use crop rotation. collapse. Use certified seed and good drainage.
at the bottom of the bulb. Browning and rotting of roots and appearance of white-pink. difenoconazole tebuconazole + trifloxystrobin Damping off fungi, Pythium spp, and Rhizoctonia spp Soil-borne pathogens that infect seedlings, leading to red-brown lesions on stems and roots, causing them to wilt and die. Constitute a major constraint for onion production during the rainy season. Use treated seeds. Crop rotation. Avoid wet soils. Favor good drainage and good soil aeration. Water only when soil is dry. No treatment threshold Use seed treated with mancozeb, thiram difenoconazole tebuconazole + trifloxystrobin Pink Root, Phoma terrestris, Soil-borne pathogen that infects seedlings, leading to pink lesions on stems and roots, causing them to wilt and die. Pink and red roots and dried out. Infected roots first turn light pink, then darken through red and purple, shrivel, turn black, and die. Eventually stunted plants. Major disease constraint for onion production. Use resistant varieties (resistance may be overcome if soil temperatures of 28°C or higher occur. Schedule planting so that the bulk of the root growth occurs prior to reaching soil temperatures that favor disease development (24-28[C) Rotate out of infested onion fields for 4-6 years. Remove weeds and plant residues. Plant in friable, well-drained soils. Do soil solarization. Ensure good soil tilth and fertility. Avoid planting onions after cereals. No treatment threshold No fungicides are recommended. Downy mildew, Peronospora destructor Downy mildew infects onions and garlic, via air-borne spores. The first symptom noticed in the field is often large circular clumps of infected plants. A fine, gray-white to purple growth appears on older leaves, becoming pale green-blue and finally yellow before stem collapse. Plastic mulch covering to avoid plant contact with soil and minimize weeds that enhance microclimate conditions favorable to disease dispersion. Heat treatment of bulbs at 35 to 40 °C for 4 to 8h reduces the disease significantly. Eliminate crop residues, plant during dry season, avoid irrigation during heat of the day. Use crop rotation. Use certified seed and good drainage. No treatment threshold found. metalaxyl mancozeb copper oxychloride
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