Young Spinach Issues: Common Diseases Of Spinach Seedlings


By: Liz Baessler

Spinach is a very popular cool season leafy green. Perfect for salads and sautés, plenty of gardeners can’t do without it. And since it grows so well in cool weather, it’s often one of the first things many gardeners plant. Keep reading to learn more about common problems with spinach seedlings and ways to recognize and manage diseases of spinach seedlings.

Common Diseases of Spinach Seedlings

Several pathogens are known to affect spinach seedlings. Although the sources are different, the result is usually the same – a condition known as either damping off or seedling blight. The symptoms of this condition include the seedling wilting and toppling over, the stem near the soil line becoming watery and girdled, and the roots becoming stunted and blackened. This is if the seedlings even manage to emerge from the ground.

Damping off can also affect seeds, keeping them from germinating. If this is the case, the seeds will have a layer of soil stuck to them by small threads of fungus. Damping off of spinach seedlings is often caused by Pythium, a family of fungus made up of several species that all have more or less the same effect.

Other pathogens, including Rhizoctonia, Fusarium, and Phytophthora, can also cause spinach damping off and seedling blight.

How to Prevent Young Spinach Disease

The pathogens that cause young spinach issues tend to thrive in cool, moist conditions. Unfortunately, spinach plants also prefer cool soil, but a lot of good can be done by planting seeds or seedlings in well-draining soil.

You can also combat harmful fungi by rotating your spinach crop with corn, and by applying fungicide at the time of seed sowing.

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Problems With Spinach Seedlings - Learn About Spinach Seedling Disease - garden

A lot of problems can happen in the garden that can confuse the average gardener. From germination, wilting, light conditions, diseases, watering, pest and much more! Below is an explanation for some of the most common problems that gardeners and farmers face when planting vegetable seeds.

Identifying and Treating Diseases

Seeds Do Not Germinate

Learning Download: Germination

This is a tricky one. Most of the time it will be an environmental condition and not the seeds. Most professional seed companies will not send seed that has been professionally tested at 85% germination. If it is just one seed variety then it may be the seed but if you have trouble with more than one it is most likely an environmental control.

Replant and make sure soil drains well

Replant and protect seed. Relocate

Seedling Wilt and Die

Learning Download: Wilt

Seedlings can be very fragile. Keeping healthy growing conditions can be a challenge for people who work, have children or just don’t have time.

Keep soil moist but not dry or damp

Usually causes root rot and plant dies where stem meets the soil

Seedlings don’t need fertilizer the first month of growth. Use a soiless mixture to start seeds

Treat with organic insecticide

Spindly and Reaching Plants

Learning Download: Spindly Plants

This is one of the most common occurrences for beginning gardeners. Tomatoes, peppers, and other vegetable stems will get long and skinny as though they are reaching for more light.

Use grow lights or sunny location. Do not burn plants.

Slow watering. Improve drainage.

Thin plants out. Increase spacing.

Do not fertilize seedlings.

Slow Growth

Learning Download: Slow Growth

Slow growth of vegetables plants can be a number of factors. Sometimes it can just be the nature of the plant to grow slow, other times it may be transplant shock.

Most vegetables need full light. Move to new location.

Use row covers or cloths to protect from cold.

Identify insect doing damage and remove pest.

Yellow Leaves

Learning Download: Yellow Leaves

Yellow leaves is a common problem on tomatoes for gardeners. It will affect other vegetables and usually means the same thing.

Most vegetables need full light. Move to new location.

Poor Yields

Learning Download: Poor Yield

Poor yields can be attributed to several things that go wrong in the garden.

Temperature too hot or cold. Grow varieties that are right for your climate.

Test soil, fix as needed. Too much nitrogen



Disease : Anthracnose
Latin binomial : Colletotrichum dematium (= Colletotrichum spinaciae , Colletotrichum dematium f. sp. spinaciae )
Host crops : Spinach.

Watersoaked lesions on spinach leaves caused by Colletotrichum dematium . Acervuli (fruiting bodies) of Colletotrichum dematium on a spinach seed. An acervulus (fruiting body) of Colletotrichum dematium showing the straight, black setae (‘hairs’) and a gelatinous mass of spores that is readily splash-dispersed.
Photo Source: Jules Riske, Osborne International Seed Co. Photo Source: Lindsey du Toit, Washington State University
Spores of the Anthracnose pathogen, Colletotrichum dematium .
Photo Source: Lindsey du Toit, Washington State University

Spinach Diseases: Field Identification, Implications, & Management Practices by Lindsey du Toit, Washington State University, presented on 23 May 2006 at the Organic Seed Alliance Spinach Seed Field Day.

Spinach: Anthracnose. UC IPM Online, University of California

Disease : Cladosporium leaf spot
Causal agent : Cladosporium variable

Very early symptoms of Cladosporium leaf spot on the cultivar ‘Ozarka II’ Necrotic lesions of Cladosporium leaf spot on ‘Winter Bloomsdale’ Severe symptoms of Cladosporium leaf spot in a spinach seed crop. Severe symptoms of Cladosporium leaf spot. Note the sporulation of the fungus in the lesions.
Photo Source:
D.A. Inglis
Photo Source: Lindsey du Toit
Symptoms of Cladosporium leaf spot (left, caused by Cladosporium variabile) vs. Stemphylium leaf spot (right, caused by Stemphylium botryosum). Symptoms of Stemphylium and Cladosporium leaf spots on a spinach plant co-inoculated with Stemphylium botryosum and Cladosporium variabile.
Photo Source: Mike Derie

Disease : Damping-off/Seedling blight
Pathogen : Aphanomyces, Fusarium, Pythium , and Rhizoctonia species.
Host crops: Most vegetables are susceptible to damping-off/seedling blight including watermelon.

Post-emergence damping-off of spinach seedlings. Note the wilted and dead seedlings in the center of the photo. Damped-off spinach seedlings washed in water to show root symptoms. Note the brown and blackened roots of damped-off seedlings compared to the white root of a healthy seedling.
Photo Source: Lindsey du Toit, Washington State University

Common Diseases: Damping-off. Washington State University Hortsense.

Disease : Downy Mildew
Pathogen : Peronospora farinosa f. sp. spinaciae

Chlorotic lesions on the upper surface of a baby leaf spinach crop infected with downy mildew. Gray-brown sporulation of Peronospora farinosa f. sp. spinaciae on a spinach cotyledon. Sporulation on the lower leaf surface. Sporangiophore and sporangia of Peronospora farinosa f. sp. spinaciae .
Photo Source: Lindsey du Toit

Disease : Fusarium wilt
Pathogen : Fusarium oxysporum f. sp. spinaciae
Host crops : Spinach. Other crops can be asymptomatic hosts, e.g., beet and Swiss chard.

Variation in severity of Fusarium wilt of spinach plants growing in soil sampled from different growers’ fields in western Washington. Typical blackening of spinach roots caused by Fusarium oxysporum f. sp. spinaciae . Spinach plants dying as a result of Fusarium wilt in a spinach seed crop in New Zealand. Longitudinal section through the root system of a healthy spinach plant (left), a spinach plant infected with Verticillium wilt (center), and a spinach plant infected with Fusarium wilt (right). Note the very light vascular discoloration caused by Verticillium wilt vs. dark, black discoloration from Fusarium wilt.
Photo Source: Lindsey du Toit, Washington State University

Disease : Stemphylium leaf spot
Causal agent : Stemphylium botryosum (asexual stage) (= Pleospora herbarum, sexual stage)

Early symptoms of Stemphylium leaf spot on the cultivar 'Winter Bloomsdale'. Necrotic, expanding lesions of Stemphylium leaf spot. Severe symptoms of Stemphylium leaf spot can resemble herbicide injury. Symptoms of Cladosporium leaf spot (left, caused by Cladosporium variabile) vs. Stemphylium leaf spot (right, caused by Stemphylium botryosum). Symptoms of Stemphylium and Cladosporium leaf spots on a spinach plant co-inoculated with Stemphylium botryosum and Cladosporium variabile.
Photo Source: Lindsey du Toit Photo Source: Mike Derie

Disease : Verticillium wilt
Causal agent : Verticillium dahliae
Host crops: Numerous vegetables including many brassica vegetables (but not broccoli), cucumber, eggplant, pepper, potato, pumpkin, radish, spinach, tomato, watermelon, etc.

Symptoms of Verticillium wilt only develop after initiation of 'bolting' (reproductive growth), and start as interveinal chlorosis of the lower leaves that progresses to interveinal necrosis. Longitudinal section through the root system of a healthy spinach plant (left), a spinach plant infected with Verticillium wilt (center), and a spinach plant infected with Fusarium wilt (right). Note the very light vascular discoloration caused by Verticillium wilt vs. dark, black discoloration from Fusarium wilt. Longitudinal section through the stem of a healthy spinach plant (left) and a spinach plant infected with Verticillium wilt (right). The plants were incubated in a moist chamber for a week after they were cut. Note the small black microsclerotia of Verticillium dahliae in the vascular tissue of the infected plant. Closeup of a spinach seed showing microsclerotia (small black spots) and mycelium of Verticillium dahliae.
Photo Source: Lindsey du Toit
Spinach seeds infected with Verticillium dahliae (six seeds with white mycelium) in a freeze-blotter seed assay.
Photo Source: Lindsey du Toit



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