Disease Control

NOTE: For the disease control products listed below, one product trade name and formulation is provided for each active ingredient (common name) as an example of rates, preharvest interval (PHI), restricted entry interval (REI), and special instructions. In many cases there are other products available with the same active ingredient. Please see Table 25 and Fungicides and Bactericides Alphabetical Listing by Trade Name for more information on products with the same active ingredients.

The symbol OG   indicates a product is listed by the Organic Materials Review Institute (OMRI) as approved for use in organic production. See Organic Certification section for more detail.

Bacterial leaf spot of cilantro (Pseudomonas syringae pv coriandricola)

The initial symptoms of bacterial leaf spot are dark, water-soaked, vein-delimited spots on leaves. The spots rapidly turn dark brown in color, remain angular in shape, and can be seen from both top and bottom sides of leaves. If disease is severe, the foliage can take on a blighted appearance when leaf spots coalesce. The disease progresses rapidly during wet weather. Cilantro crops with significant amounts of this disease will be unmarketable. The causal bacterium is host specific to cilantro and does not infect celery or parsley. The pathogen is seedborne in cilantro. Thus, infested seed is the primary means by which the pathogen gets into the cilantro production system. The bacterium can also survive many years in the soil as an opportunistic bacterium. If bacterial leaf spot has been a problem, rotate out of cilantro for several years. Use management practices that promote airflow and do not work in this crop when wet. For both conventional and organic cilantro, the only foliar treatment available is a copper fungicide.

Bacillus amyloliquefaciens Strain D747 (DoubleNickel 55): 0.25 to 3.0 lb/A; PHI 0d, REI 4, Group 44.

basic copper sulfate (Cuprofix Ultra 40 Disperss): 2.0 lb/A; PHI 0d, REI 48h, Group M1.

Powdery Mildew (Leveillula lanuginosa)

Disease development is favored by high humidity, moderate temperatures, and drought stress. Rain or overhead irrigation reduces disease severity. The pathogen can survive between crop cycles. Control wild and volunteer Apiaceae plants. Maintain adequate fertilizer and irrigation programs to ensure plant health. Drought stress may be lessened by mulching. Use resistant cultivars when available.

Root rot (Pythium and Phytophthora spp.)

These pathogens are soil-borne and most severe in cold, wet soils. Look for collapsed plants shortly after emergence. Provide good soil drainage and reduce soil compaction; raised beds may be useful.

mefenoxam (Ridomil Gold SL): 1.0 to 2.0 pt/A; PHI 21d, REI 48h, Group 4.

Trichoderma asperellum, T. gamsii (Bioten 2.0OG): See label for in-furrow, drench, and broadcast rates; REI 1h, Group NC.

Septoria blight (Septoria petroselini)

Severe disease can destroy crop quality. Symptoms appear as small lesions with small black specks in the center. The pathogen is seedborne and highly favored by rain and overhead irrigation. Start with certified, disease free seed or treat seed with hot water or fungicides. Inspect transplants before setting in the field and destroy infected plants. Rotate to crops outside of the Apiaceae family. Plant sequential plantings as far apart from one another as possible. Incorporate plant residues promptly after harvest.

White Mold (Sclerotinia sclerotiorum)

Start with certified seed that is free from sclerotia of the pathogen. Infected plants will wilt with a white, cottony fungal mass near the soil line. Rotate with non-host plants. Irrigate in the morning to promote drying of soil and foliage. This pathogen thrives in 50-70 ˚C temperatures and cool, damp conditions. Ten or more days of wet soil promotes infection. Soil sterilization with heat, chemicals, steam, or by biofumigation with brassica crops can reduce, but not eliminate, sclerotia.

Trichoderma asperellum, T. gamsii (Bio-tam 2.0OG): See label for in-furrow, drench, and broadcast rates; REI 1h, Group NC.