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Spinach
Scientific name:
Spinacia oleracea
Order/Family:
Caryophyllales: Chenopodiaceae
Importance:
medium
Pests and Diseases (clicking takes you to the pest and disease pages):
Bacterial soft rot
White rust, Cucumber Mosaic Virus (CMV)
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 Geographical distribution indicated in red
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General Information on Spinach Agronomic AspectsInformation on Major Pests and DiseasesInformation Source Links
Climatic conditions, soil and water management:
Optimum growing temperatures are 15-20°C. Vegetative growth is retarded by temperatures above 27°C. It does not suit the lowlands and grows best where the temperature varies between 10 and 20°C or above 2000 m altitude. It is frost resistant. Soils should be light in texture, well-drained, rich in organic matter and with a pH 6-7.5 (EcoPort). Varieties
- "Early Hybrid No. 7": It is an upright, compact and prolific plant. The leaves are dark green, semi-savoyed, and comparatively large with short petioles. It is early maturing and highly productive. It is tolerant to downy mildew and has a very good regeneration ability.
- "Bloomsdale Long Standing": It is an upright compact plant. It has thick fleshy leaves, which are dark green, savoyed, large and with very long petioles. It is vigorous and an exceptionally long standing variety.
- "Giant Noble": It is a dwarf plant, fast growing but produces moderate yields. The leaves are smoth, thick, mid-green with short petioles.
- "King of Denmark": It is a spreading plant, very prolific and vigorous. The leaves are smooth, thick, mid-green, medium sized with long petioles.
- "New Zealand Spinach": It is a hardy, low spreading, branching plant. It has numerous leaves, which are triangular, thick, fleshy, dark green and are smaller than other varieties. The seeds are large. Prickly, and germinate slowly. It does well in hot, dry climates. It produces large amounts of greens over a long period hence best suited for kitchen gardens.
Propagation and planting
Transplants are not used commercially, but are good for home gardens. All commercial production is direct seeded with little or no thinning. The seed is either broadcast or sown in rows on wide beds. There should be 5-15cm in between plants in the row. The distance between rows should be 30- 90cm. Spinach seeds need consistent soil moisture for proper germination (University of Georgia). Husbandry
In temperate areas two types of spinach are recognised, the round seeded type, usually sown in the spring and harvested in the summer, and the hardier prickly seeded type sown end of summer or beginning of fall for use in the winter and spring. Spinach needs high doses of N and K as well as a regular water supply throughout the season for optimum yield and quality. Summer crops may be intercropped with other vegetables to benefit from shade (CAB 2006). Harvesting
Whole plants with 8-10 leaves are harvested, the roots are cut one cm below the plant base and the product is sold in bundles of 10-15 plants (CAB 2006).Downy mildew (Peronospora spinaciae / Peronospora farinosa)
This fungus is distributed worldwide. It causes leaf spotting that detracts from the quality and appearance. Leaf spots begin as indefinite yellowish areas on the upper leaf surface. A mat of grey to violet mould develops on the corresponding lower surface. With time under cool, wet conditions, the spots enlarge until the whole turns black and dies. The fungus increases profusely in high humidity. The spores can overseason in mild climatesin living spinach, in seeds and in the soil.
What to do:
- Use resistant varieties (e.g. "Early Hybrid 7")
- Use certified disease-free seeds. If using own seeds, treat seeds with 500°C for 25 minutes.
- Practice at least a 3-year rotation and plant in well-drained soil.
Bacterial soft rot (Erwinia carotovora)
It is one of the most important diseases. Its symptoms include water soaked tissue and muddy-green or greasy appearance of leaves. Rapid decay occurs and the tissue becomes wet and mushy. This bacterium is found in the soil and in plant debris. It can enter into the plant through mechanical injury, insect injury, disease lesions and other skin punctures.
What to do:
- Practice rotation with maize, beans, small grains and grasses.
- Care at harvesting and handling to avoid bruising
- A storage temperature just above freezing (0°C) and a relative humidity below 90% does much to reduce soft rot losses
- Storage rooms, dump tanks and boxes should be disinfected each season with copper sulfate
Fusarium wilt (Fusarium oxysporum f. sp. spinaciae)
It is a wilt that is caused by a fungus. Plants can be affected anytime after the tree-leaf stage. Foliage loses its green luster, gradually wilts and turns yellow, beginning with the oldest leaves. The fungus is soil-borne and seed-borne. It commonly occurs where temperatures are fairly high. It can live in the soil indefinitely and there rotation is not effective in its control.
What to do:
- Use resistant varieties where available
- Use certified disease-free seeds
White rust (Albugo occidentalis) It is a fungus that causes white blister-like pustules on the underside of leaves. They are filled with white spores and the surrounding tissue turns brown and dies.The fungus favors clear, warm, and dry days with cool nights.
What to do:
- Use resistant varieties where available
- Use certified disease-free seeds
- A 3-year rotation is recommended
Cucumber Mosaic Virus (CMV)
It is transmitted by the green peach aphids. Symptoms begin as a mottling of the younger inner leaves, which later change to a yellow colour. The symptoms gradually appear on outer leaves, which also change to yellow. The affected leaves curl and wrinkles. Severely affected leaves die. If a plant is affected at the seedling stage, its growth is stunted. The dwarfing, yellowing, corrugation and leaf death are conspicuous symptoms of the disease different from other diseases attacking spinach.
Intensity of the virus increases under long days and intense light. This virus affects, in addition to spinach, a wider group of vegetables, flowers, weeds and ornamentals than any other virus. At least 34 plant families are included as hosts.
What to do:
- Use resistant varieties (e.g. "Early Hybrid 7")
- Control aphid vectors throughout the growing season.
- Control weeds
For more information on aphids click here.
The green peach aphid (Myzus persicae)
It is a very detrimental insect to spinach. It can transmit diseases that can wipe out large portions of the crop. Aphids and leafminers cause the most serious damage on the crop (University of Georgia). The aphid is pale yellowish in color and small. It lives mainly on the underside of leaves and therefore hard to control.
What to do:
- Conserve natural enemies. Parasitic wasps and predatory insects, including lady bird beetles, damsel bugs, lacewings, and hover fly larvae are important in natural control of aphids. For more information on natural enemies click here
- CAB International (2005). Crop Protection Compendium, 2005 edition. Wallingford, UK www.cabi.org
- Ministry of Agriculture and Rural Development, Kenya and Japan International Cooperation Agency, (2000). Local and Export Vegetables: growing Manual. Printed by Agricultural Information Resource Centre, Nairobi, Kenya
- Plants For A Future, 1996-2003. http://www.pfaf.org/database/plants.php?Spinacia+oleracea
- Sherf, A. F. and Macnab, A. A. (1986). Vegetable Diseases and Their Control. John Wiley & Sons, Inc. ISBN: 0-471-05860-2.
- University of Georgia, College of Agricultural and Environmental Sciences, Department of Horticulture http://www.uga.edu/vegetable/spinach.html
