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, days to harvest (dh), REI, and special instructions. In many cases, there are other products available with the same active ingredient. Please see Table 28 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 details.

Cladosporium Leaf Spot (Cladosporium variable)

Cladosporium leaf spot caused by Cladosporium variabile is considered to be of minor importance in spinach crops, but can be severe in spinach seed production and has become a problem in high tunnels. The most conducive environment for disease development is cool and moist with temperatures between 59° to 68°F and relative humidity above 80%. However, the fungus can grow under a wide range of temperatures, ranging from 41° to 86°F.  The epidemiology of this disease is not well known. Spinach seeds carry the fungus, but it has not been determined whether the disease is transmitted via contaminated seed to soil or seedlings. It is also not known how long the fungus can survive on spinach residues in soil or in weed hosts. Cladosporium has been recovered from dried leaves and seed stocks up to eight years old. Cultural controls rely mainly on sanitation--the removal of infected plants, spinach debris, spinach volunteers, and unused seed. Start with certified, disease-free seed or treat seed with hot water or bleach to reduce seedborne inoculum. There are difference in cultivar susceptibility with 'Winter Bloomsdale' more resistant than 'Fall Green' and 'Ozarka'.

penthiopyrad (fontelis SC): 14 to 24 fl oz/A. (3 dh, REI 12h, Group 7).

Downy Mildew (Peronospora farinosa)

Downy mildew is considered the most important disease of spinach and is favored by cool, moist conditions. Incidence of the disease appears to be increasing due to the increased use of high tunnels for spinach production.  The potential overlap of field spinach and high tunnel spinach can create a “green bridge” for the disease, allowing the pathogen to transfer between field and high tunnels. The pathogen will not survive without a live host. Reducing humidity and leaf wetness along with the use of resistant varieties will minimize the incidence of the disease. There are several races of the pathogen with Race 14 recently surfacing in New England high tunnels. Downy mildew management relies on resistant varieties (select resistance to Races 1-15 if possible) and once infected, there is little that can be done. Rotate out of spinach for at least two years.

acibenzolar-S-methyl (Actigard): 0.5 to 0.75 oz/A. (7 dh, REI 12, Group 21).

ametoctradin plus dimethomorph (Zampro): 14.0 fl oz/A. (0 dh, REI 12h, Groups 45 & 40).

azoxystrobin (Quadris): 12.0 to 15.5 fl oz/A. (0 dh, REI 4h, Group 11). Rotate with a fungicide other than a strobilurin. Quadris can by phytotoxic to spinach. See label for precautions.

cupric hydroxide (Kocide 3000): 0.75 to 1.25 lb/A. (0 dh, REI 48h, Group M1). Flecking may occur on spinach leaves.

cymoxanil (Curzate 60 DF): 5.0 oz/A. (1 dh, REI 12h, Group 27). Use only in combination with a protectant fungicide.

famoxadone plus cymoxanil (Tanos 50 DF):  8.0 to 10.0 oz/A. (1 dh, REI 12h, Groups 11 & 27). Must be tank mixed with an appropriate contact fungicide with a different mode of action. Do not alternate or tank mix with other Group 11 fungicides.

fenamidone (Reason): 5.5 to 8.2 fl oz/A. (2 dh, REI 12h, Group 11).

fluopicolide (Presidio): 3 to 4 fl oz/A. (2 dh, REI 12h, Group 43). Must be used in a tank mix with a fungicide with a different mode of action.

fluxapyroxad + pyraclostrobin (Merivon): 6-11 fl oz/A. (11 dh, REI 12h, Groups 7 & 11). For suppression only.

fosetyl aluminum (Aliette WDG): 2 to 5 lb/A (3 dh, REI 12h, Group 33).

mandipropamid (Revus): 8.0 fl oz/A. (1 dh, REI 4h, Group 40).

mefenoxam (Ridomil Gold SL): 0.25 pt/A. (21 dh, REI 48h, Group 4). Must be applied pre- and post-plant for effective control of Downy Mildew. Incorporate into soil mechanically or with irrigation. See label for instructions and precautions.

phosphorous acid (Fosphite): 1.0 to 3.0 qt/100 gal. (0 dh, REI 4h, Group 33).  Do not apply to plants that are heat or moisture stressed or recently treated with copper products.

pyraclostrobin (Cabrio EG): 12 to 16 oz/A. (0 dh, REI 12h, Group 11).

Seed Decay

Buy treated seed. Do not use treated seed for food, feed or oil purposes.

fludioxonil (Maxim 4FS): 0.08 to 0.16 oz/00 lb seed. (REI 12h, Group 12). For protection against seed-borne and soil-borne fungi. Does not control Pythium and Phytophthora.

mefenoxam (Apron XL): 0.085 to 0.64 fl oz/100 lb seed. (REI 48h, Group 4). For Pythium damping-off protection.

thiram (Thiram 42 S): 8.0 lb/100 lb seed.  (REI 12h, Group M3).

Streptomyces grieoviridis strain K61 (MycoStopOG):  0.08 oz/lb seed.

Stemphylium Leaf Spot (Stemphylium botryosum)

This new disease of spinach was first detected in California in 2001. It affects both production spinach and spinach seed crops, and has become a problem in high tunnel production. Details on the pathogen's life cycle are lacking, although the pathogen is seedborne. In the field, the disease spreads slowly and damage is limited. Cultural controls rely mainly on sanitation--the removal of infected plants, spinach debris, spinach volunteers, and unused seed. Start with certified, disease-free seed or treat seed with hot water or bleach to reduce seedborne inoculum.

penthiopyrad (Fontelis): 14 to 24 fl oz/A. (3 dh, REI 12h, Group 70.

White Rust (Albugo occidentalis)

A very damaging disease of spinach that is found only east of the Rocky Mountains in the USA. Plant resistant cultivars and practice crop rotation. Apply preplant and foliar fungicides.

acibenzolar-S-methyl (Actigard): 0.5 to 0.75 oz/A. (7 dh, REI 12, Group 21).

azoxystrobin (Quadris): 6 to 15.5 fl oz/A (0 dh, REI 4h, Group 11). Quadris can by phytotoxic to spinach. See label for precautions.

cupric hydroxide (Kocide 3000):  0.75 to 1.25 lb/A. (0 dh, REI 48h, Group M1). Flecking may occur on spinach leaves.

cyazofamid (Ranman 400 SC): 2.75 fl oz/A. (0 dh, REI 12h, Group 21).

famoxadone plus cymoxanil (Tanos):  8.0 to 10.0 oz/A. (1 dh, REI 12h, Groups 11 & 27). Must be tank mixed with an appropriate contact fungicide with a different mode of action. Do not alternate or tank mix with other Group 11 fungicides.

fenamidone (Reason): 5.5 to 8.2 fl oz/A. (2 dh, REI 12h, Group 11).

fosetyl aluminum (Aliette WDG): 2 to 5 lb/A. (3 dh, REI 12h, Group 33).

fluopicolide (Presidio): 3 to 4 fl oz/A. (2 dh, REI 12h, Group 43). Must be used in a tank mix with a fungicide with a different mode of action.

mefenoxam (Ridomil Gold SL): 0.25 pt/A. (21 dh, REI 48h, Group 4). Must be applied pre- and post-plant for effective control of white rust.  Incorporate into soil mechanically or with irrigation. See label for instructions and precautions.

Cucumber Mosaic Virus (CMV)

CMV is found worldwide and infects over 800 crop and weed hosts.This disease is transmitted by aphids in a nonpersistent manner; insecticides are in no value in controlling this disease. Start with virus-free seed. Eliminate weeds such as chickweed, pokeweed, and milkweed. Grow resistant varieties such as Blight Resistant Savoy, Savoy Hybrid 612 and Melody.