Broad mites are tiny (0.1-0.2 mm long) and cannot be seen with the naked eye, and are even difficult to detect with a hand lens.
An attack by the broad mites can be detected by the symptoms of damage.
They live on the underside of leaves, tender stems, fruits, flower peduncles and flowers. Their feeding produces discolouration, necrosis of tissues and deformation.
Initial attack occurs on the stems of terminal shoots and the lower surface of young leaves.
Young leaves turn narrow, twisted or crumpled, fail to elongate and finally may wilt and dry, giving the plant a scorched appearance.
Older leaves are generally cupped with corky brown areas between the main veins on the lower side of the leaves.
The succulent part of the stem of young plants may become slightly swollen, roughened or russeted. The foliage becomes rigid.
Attacked fruits become deformed with a cork-like surface or fail to develop. Severely infested fruits fall, and yield is significantly reduced.
Symptoms remain for a long period of time after control.
What to do:
Broad mites are attacked by predacious mites. Phytoseiulus persimilisis not very much attracted to broad mites. Amblyseius spp are better predators of broad mites, in particular A. californicus is used for control of broad mites in different parts of the world.
Broad mites can be effectively controlled with sulphur sprays. However, sulphur is toxic to predatory mites.
Geographical Distribution of Peppers in Africa. Updated on 10 July 2019. Source FAOSTAT
General Information and Agronomic Aspects
Capsicum peppers (mainly Capsicum annuum, Bell pepper and capsicum frutescens, Chilli pepper) are the most popular and most widely used condiment all over the world.
The genus Capsicum consists of all the ‘chilli pepper plants’ with 3-5 wild species and over 2000 cultivars.
Its fruits are consumed in fresh, dried or processed form as table vegetable or spice.
Capsicum peppers are extensively pickled in salt and vinegar. Colour and flavour extracts are used in both the food and feed industries, for example, ginger beer, hot sauces and poultry feed, as well as for some pharmaceutical products.
Sweet, non-pungent capsicum peppers are widely used in the immature, green-mature or mature-mixed-colours stage as a vegetable, especially in the temperate zones.
Capsicum extracts show promise against some crop pests.
Climate, soil and water management
Climatic requirements and cultural practices for production of sweet peppers and chillies are the same.
They also share a same complex of pests and diseases. Capsicum peppers tend to tolerate shade conditions up to 45% of prevailing solar radiation, although shade may delay flowering.
Capsicum peppers grow best on well-drained loamy soils at pH 5.5-6.8. They grow at a wide range of altitudes, with rainfall between 600 and 1250 mm.
Severe flooding or drought is injurious to most cultivars. Seeds germinate best at 25-30degC.
Optimal temperatures for productivity are between 18 and 30degC. C. frutescens are more tolerant to high temperatures.
Cooler night temperatures down to 15degC favour fruit setting, although flowering will be delayed as temperatures drop below 25degC.
Flower buds will usually abort rather than develop to maturity if night temperatures reach 30degC.
Pollen viability is significantly reduced at temperatures above 30degC and below 15degC.
Propagation and planting
Capsicum peppers are propagated by seed. Seeds should be harvested from mature fresh fruit after 2 weeks of ripening after harvest.
Seeds remain viable for 2-3 years without special conservation methods if they are kept dry.
They rapidly lose viability if they are not properly stored especially at high temperature or humidity.
Seed dormancy may occur to a small extent, especially if seed is harvested from under-ripe fruits.
Some 200-800 g of seed is required per ha, depending on plant density. When using own seeds, hot-water treat the seeds.
Seedbeds are usually covered with straw, leaves or protective tunnels. For better production, seedlings should be transferred to seedling pots (plastic pots, paper cups, banana leaf-rolls, etc.) when the cotyledons are fully expanded.
Transplants are planted out in the field at the 8-10 true leaf stage, usually 30-40 days after sowing. Hardy transplants can be produced by restricting water and removing shade protection, starting 4-7 days before transplanting.
Transplanting should be done during cloudy days or in the late afternoon, and should be followed immediately by irrigation.
Direct sowing in the field is practised to a limited extent. Capsicum peppers are well adapted to sole cropping and intercropping systems.
Capsicum peppers are often relay-cropped with tomatoes, shallots, onions, garlic, okra, Brassica spp. and pulses.
They also grow well among newly established perennial crops.
Cultivars commonly grown in Kenya:
Sweet pepper (C. annuum):
California Wonder
Yolo wonder
Emerald Giant
Ruby Giant
Hot pepper (C. frutescens)
Anaheim
Fresno
Jalapeno
Long Red Cayenne
Rocket
Short Bullet
Husbandry
Capsicum peppers thrive best if supplied with a generous amount of organic matter. A reasonable recommendation is to supply 10-20 t/ha of organic matter.
General nutrient requirements are 130 kg/ha of N, 80 kg/ha of P and 110 kg/ha of K. Nutrient availability is subject to soil type and environmental conditions, so local recommendations vary.
Manual weeding is usual for weed control. It is most critical at the reproductive phase.
Organic or plastic mulches are very effective for weed control, and reflective mulches help to minimise insect vectors of plant viruses. Staking can help minimise lodging.
Capsicum peppers may be grown under rain-fed or irrigated conditions.
To avoid certain diseases, pests or allelopathic damage, capsicum peppers should not be planted after other solanaceous crops, sweet potato or jute.
Harvesting
Capsicum peppers are ready for harvest 3-6 weeks after flowering depending on the fruit maturity desired.
Green fruits are mature when firm, if gently squeezed they make a characteristic popping sound.
Harvesting is done by hand or with the aid of a small knife. Sweet capsicum peppers are often harvested at the green mature stage, although sometimes they are harvested red.
Assorted fruit colours such as yellow, orange, chocolate and purple are also available in specialised markets. Hot capsicum peppers are harvested green or red depending on their utilisation.
For the fresh market, fruits are harvested mature but firm, whereas capsicum peppers sold as dried pods may be left to partially dry on the plants before harvesting.
Yields under irrigated conditions tend to be higher than for rain-fed production, but vary with other management practices. Unless sold for the fresh market, hot capsicum peppers can be sun-dried.
Sun-drying usually takes place in a vacant field or roadside, on mats or a well-swept area.
In the sun, capsicum peppers will dry adequately in 10-20 days, with frequent turning of fruits. Steaming of hot and capsicum pepper before being sun-dried tends to improve the appearance, making dried fruits look glossy.
East African Seed Co. Ltd. Africa’s Best Grower’s Guide www.easeed.com
Herold, W. (1919). A contribution to the knowledge of Agrotis segetum, Schiff. Zeitschrift fur angewandte Entomologie, 1:47-59.
Madge, D., Jaeger, C., Clarke, S. (2003). Agriculture notes. Organic farming: Carrot production and marketing. State of Victoria, Department of Primary Industries. www.dpi.vic.gov.au
Ministry of Agriculture and Rural Development (Kenya) and Japan International Cooperation Agency (2000). Growing Manual for Local and Export Vegetables. Reprinted by Agricultural Information Resource Centre (Nairobi, Kenya). 274 pp.
Neergaard P. (1945). Danish Species of Alternaria and Stemphylium. London, UK: Oxford University Press.
Nutrition Data www.nutritiondata.com.
Pests of carrot: www.ipm.ncsu.edu
Sherf, A. F., Macnab, A. A. (1986). Vegetable Diseases and Their Control. 2nd. Edition. A Wiley-Interscience Publication. ISBN: 0 471 05860 2
University of Illinois Extension. www.urbanext.uiuc.edu
Cottony soft rot (Sclerotinia sclerotiorum). Greyish, white mold forms at the base of stem. Black round structures appear as disease progresses. The disease can extend underground to the root. (c) David B. Langston, University of Georgia, Bugwood.org
Leaf blight
Leaf blight (Alternaria dauci). Small, irregular, black to purplish coloured spots. Spots may coalesce to cover the entire leaf. (c) David B. Langston, University of Georgia, Bugwood.org
Powdery mildew
Powdery mildew on carrot caused by Erysiphe heraclei (c) www.poljoberza.net
Damping-off on carrot
Damping-off on carrot (Phythium sp.) (c) David B. Langston, University of Georgia, www.bugwood.org
Bacterial soft rot
Bacterial soft rot caused by (Erwinia carotovora var. carotovora) on carrot (c) Oregon State University
Powdery mildew on carrot caused by Erysiphe heraclei (c) www.poljoberza.net
The disease is caused by the fungus Erysiphe polygoni (E. heraclei).
It is characterised by the development of white, powdery fungal growth on leaves. Affected leaves become chlorotic and eventually die. The fungus is seed-borne.
What to do:
Use certified disease-free seeds if using own seeds hot water treat the seeds.
Practise good field hygiene.
Practise over-head irrigation where feasible.
Spray with sulphur based products where acceptable.
Bacterial soft rot caused by (Erwinia carotovora var. carotovora) on carrot (c) Oregon State University
Erwinia carotovora subsp. carotovora is a bacterium. Bacteria survive in decaying refuse and enter the root principally through cultivation wounds, harvest bruises, freezing injury, and insect openings.
After infection, high humidity is essential for progress of the disease.
When soft rot occurs in the field, it usually follows a period of water logging in low areas following excessive rain or irrigation.
Carrots, potatoes, onions, crucifers, and celery are only a few of the many plants attacked.
The disease causes a soft, watery, slimy rot. The rotted tissues are grey to brown and may have a foul odour.
It decays the core of the root. Also prolonged wet weather favours disease development.
It is a serious transit and storage problem if affected carrots are not discarded.
In the field, tops of rotted carrots turn yellow and wilt as roots break down.
What to do:
Follow a crop rotation of cereals and fodder grasses.
Destroy by burning of infected plants.
Carefully handle carrots at harvesting to minimise bruising.
Discard affected carrots before transport and storage.
Damping-off on carrot (Phythium sp.) (c) David B. Langston, University of Georgia, www.bugwood.org
Damping-off diseases are caused by a complex of plant pathogens (disease inciting agents) including Alternaria spp., Fusarium spp., Pythium spp. and Rhizoctonia solani. These pathogenic fungi may cause rotting of seeds before emergence or death of seedlings after emergence.
The most disposing factors are use of non-certified disease-free seeds and excessive watering of seed-beds or field plots.
What to do:
Always use certified disease-free seeds. If using own seeds hot water the seeds.
Leaf blight (Alternaria dauci). Small, irregular, black to purplish coloured spots. Spots may coalesce to cover the entire leaf. (c) David B. Langston, University of Georgia, Bugwood.org
The disease is caused by the fungus Alternaria dauci. Dark-grey to brown, angular spots form on leaves. Surrounding tissue yellows and affected leaves eventually die.
Older leaves are attacked first and only in very severe cases are younger leaves affected. Large spots can girdle leaf petioles and kill leaves without spots developing on individual leaflets.
During warm moist weather, dying of affected leaves may occur so rapidly that plants appear scorched.
This fungus can also cause seedling damping-off. The fungus is seed-borne and survives in the soil crop debris.
What to do:
Use resistant hybrids where available.
Use certified disease-free seeds. In case of using own seeds hot water treat seeds.
Avoid parsley in crop rotation and practice good field hygiene.
Enhance aeration of crop field by less dense crops and ridge cultivation.
No or little N-fertilisation.
Monitor fields regularly to be able to react properly.
Cottony soft rot (Sclerotinia sclerotiorum). Greyish, white mold forms at the base of stem. Black round structures appear as disease progresses. The disease can extend underground to the root. (c) David B. Langston, University of Georgia, Bugwood.org
The disease is caused by the fungus Sclerotinia sclerotiorum and is characterised by development of soft, watery rot of leaves, crowns and roots.
Affected areas become covered with white, cottony fungal growth in which black, irregular, fungal resting bodies (sclerotia) form.
The sclerotia enable the fungus to survive for long periods in the soil. This disease is a serious field and storage problem.
If diseased roots are packed, extensive breakdown may occur during transit and storage.
What to do:
Practice 3-year rotation using cereals and forage grasses.
Soil flooding is helpful where feasible.
Do not pack and store damaged and or diseased roots.
Use clean containers in storage.
Maintain temperature near 0degC and a relative humidity no higher than 95% during storage.
