Symptoms or Damage Management Pests Leafminers, Damage caused by leafminer Natural enemies, especially Liriomyza spp. is primarily cosmetic in parasitic wasps, are . green bunching onions; commonly found reducing contamination by pupae and leafminer numbers. These larvae, however, is a parasitic wasps are very problem susceptible to insecticide Damage in dry onions and sprays, however, and may garlic is of little concern not be important in fields unless populations become where insecticides have been so high as to prematurely used. kill foliage. Purple Blotch, The margin or leaf has Use Dethane 45, Manzate Alternaria porri shades of red purple 200, WP and other and Stemphylium surrounded by a yellow recommended fungicides. Leaf Blight, band. The infected leaves The frequency and dosage Stemphylium turn yellow. of application are indicated vesicarium in their labels. Stemphylium leaf blight, the disease isfavored by heavy rainy weather . These diseases are often associated with downy mildew lesions on onions; they occur less commonly on garlic. Infection of seed stalks can reduce seed yield and quality Cercospora leaf Lesions penetrate through Use of copper-based spot, Cercospora the young leaves. They start may be able to duddiae as small circular chlorotic control this disease. spots 3-5 mm in diameter. After a fusion of the original lesions, the disease progresses rapidly and eventually the leaf dies. Fusarium bulb rot, The leaves of the affected Use disease-free planting Fusarium plants show progressive materials. oxysporum F cepae yellowing and drying from Burn field refuse. (Hanzwa),Snyder the tip. Rotate the crop at least every and Jausen At the advance stage of the four years. disease, roots and bulb show Fallow the field for one semi-watery rotting season. Plow and harrow or rotavate the area several times for the whole dry season.
Pests Symptoms or Damage Management Leafminers, Liriomyza spp. . Damage caused by leafminer is primarily cosmetic in green bunching onions; contamination by pupae and larvae, however, is a problem Damage in dry onions and garlic is of little concern unless populations become so high as to prematurely kill foliage. Natural enemies, especially parasitic wasps, are commonly found reducing leafminer numbers. These parasitic wasps are very susceptible to insecticide sprays, however, and may not be important in fields where insecticides have been used. Purple Blotch, Alternaria porri and Stemphylium Leaf Blight, Stemphylium vesicarium The margin or leaf has shades of red purple surrounded by a yellow band. The infected leaves turn yellow. Use Dethane 45, Manzate 200, WP and other recommended fungicides. The frequency and dosage of application are indicated in their labels. Stemphylium leaf blight, the disease isfavored by heavy rainy weather . These diseases are often associated with downy mildew lesions on onions; they occur less commonly on garlic. Infection of seed stalks can reduce seed yield and quality Cercospora leaf spot, Cercospora duddiae Lesions penetrate through the young leaves. They start as small circular chlorotic spots 3-5 mm in diameter. After a fusion of the original lesions, the disease progresses rapidly and eventually the leaf dies. Use of copper-based may be able to control this disease. Fusarium bulb rot, Fusarium oxysporum F cepae (Hanzwa),Snyder and Jausen The leaves of the affected plants show progressive yellowing and drying from the tip. At the advance stage of the disease, roots and bulb show semi-watery rotting Use disease-free planting materials. Burn field refuse. Rotate the crop at least every four years. Fallow the field for one season. Plow and harrow or rotavate the area several times for the whole dry season.