Potato

• Conserve natural enemies. They are important in natural control of aphids. (Link to natural enemies datasheet).
• Control aphids in potato planted for seed production.
• Site seed production areas in locations with low temperature, abundant rainfall and high wind velocity. Aphid populations are generally low under these conditions.
• Within a potato growing area, locate seed potato fields upwind from commercial potato fields and alternative host crops to reduce dissemination of viruses through aphids carrying viruses.
• Keep seed production areas separated from commercial potato production.
• Check the field regularly. Monitoring of aphid build-up is important.
• Protect young plants from aphid attack. Virus spread early in the season is more serious than later on, as young plants are generally more susceptible. Moreover, plants that are infected early become more efficient sources for further virus spread than plants infected later in the season.
• Harvest seed potatoes no later than 8 to 10 days after a critical aphid build-up or increased virus infection rates are noted. This may help to avoid infection since the virus requires time to infect the tubers after a virus-carrying aphid has fed on potato foliage.
• Remove yellow flowering weeds and any other host plants within and around the field. Aphids are attracted to yellow colour.
• Protect potato tubers during storage by preventing access of aphids. Potato aphids readily colonise tuber sprouts. Seed potatoes are very susceptible to infection at this stage.
• Neem products are useful for reducing aphid populations on potatoes. In Sudan, 2 applications of seed extracts at a rate of 1kg seed kernels/40l water at a 14 days interval reduced aphid (A. gossypii) population to 60% compared to the control (Zebitz, 1995).
• Extracts of the weed Artemisia vulgaris have also shown toxicity to potato aphids (Metspalu and Hiiesar, 1994).

• Use resistant varieties where available. This constitutes the best management strategy.
• Use healthy seed tubers and avoid injury to the tubers.
• Avoid excess watering.
• Store and transport tubers in dry, well ventilated conditions.
• Practise field hygiene.

• Use clean certified disease-free seed.
• Plant resistant varieties where available.
• Remove wilted plants to reduce spread of the disease from plant to plant.
• Bio-fumigation (incorporating especially mustard or radish plants in large amounts into the soil immediately before planting potatoes) helps in reducing and the long-term elimination of bacterial wilt from the soil. This practice is reported to reduce incidence of bacterial wilt by 50 to 70% in the Philippines (ACIAR 2005/6). For more information on biofumigation click here
• Do not grow crops belonging to the same family as potatoes (e.g. tomatoes, peppers or eggplant) in succession in the same land. Rotation is not effective against bacterial wilt because the pathogen can survive for several years in the soil and also can infect a wide range of crops and weeds. However, the disease incidence can be reduced if crop rotation with non-susceptible crops (e.g. cereals) is combined with the other above-mentioned control components.

• Protect plants by wrapping them with collars. A simple collar can be made from cardboard tubes from paper towels or toilet paper (cut to size). This practice is time consuming, but it is effective and practicable in small fields.
• If necessary spray neem extracts. Neem leaf extracts and neem seed extracts (1 kg/40 l water) have been effective against cutworms attacking potatoes reducing damage significantly in Sudan.

• Use certified disease-free seeds
• Practise rotation with non-solanaceaous crops.
• Practise good field hygiene. Remove infected leaves during the growing season and discard all badly infected potato plant debris at the end of each season.
• Avoid overhead irrigation and lay down a thick organic mulch to prevent soil splashing onto lower leaves.

• Handpick and destroy adults and larvae of Epilachna beetles. This is feasible in small plots.
• Spray neem extracts. Simple neem-based pesticides have been reported to control Epilachna beetles on several crops. Thus, sprays with an aqueous neem seed extract (10g/l) at 10 days intervals showed repellent effect on these beetles in India. In Togo, feeding by Epilachna beetles in squash and cucumber could be reduced significantly by weekly applications of aqueous neem kernel extracts at concentrations of 25, 50 and 100 g/l and neem oil applied with an ultra-low-volume (ULV) sprayer at 10 and 20 l/ha (Ostermann and Dreyer, 1995).

• Plant resistant varieties where available. In Kenya, varieties "Tigoni", "Kenya Baraka", "Roslin Eburu", "Annet" and "Asante" are claimed to have some resistance to late blight.
• Practise rotation with non-solanaceaous crops (do not rotate with tomatoes and eggplants).
• Practise good field hygiene. Pull up and discard infected plants.
• Select only, certified, disease-free seed potatoes and never plant table-stock potatoes
• Keep foliage dry and avoid overhead irrigation.
• Plant potatoes in sunny, well-drained locations.
• KARI has also conducted studies to evaluate lower cost measures used by farmers to control late blight, including the application of a mixture made of stinging nettle (possibly Urtica massaica, though not indicated) and Omo (presumably the commercial brand of laundry detergent). Although this treatment was not as effective as a commercial fungicide, Ridomil, blight scores were nevertheless lower and yields higher than observed for the control. On a benefit to cost basis, the stinging nettle treatment was impressive, at over two to one (KARI 2000). This treatment is apparently not a common practice in Kenya, at least not yet, but an example of using stinging nettle (Urticaria dioica) as a treatment against late blight in Sweden is reported in Ecology and Society.

• Clear hiding places. Remove volunteer plants, crop residues, decaying vegetation, dead leaves, grass, compost piles, excess mulch or other similar debris. Litter under trees, abandoned termite hills, and neglected home nurseries can also harbour large populations of millipedes.
• Avoid wet areas
• Trap millipedes. They like hiding during daytime. They can be attracted by placing flat objects (such as pieces of plywood) on the ground where they hide under and can be collected subsequently.

• Plant certified potato seeds
• Avoid planting potatoes for up to 7 years in infested fields.
• Practice crop rotation
• Trap cropping - planting a crop of potato to stimulate the eggs to hatch and then removing the plant before the nematodes can complete their life cycle.

• Plant certified disease-free seed tubers.
• Plant whole seed tubers instead of cut pieces.
• Remove infected plants from the field.

• Conserve natural enemies. They are important for natural control of the potato tuber moth. Ladybird beetles prey on eggs and young caterpillars. Larvae of lacewings, big-eyed bugs, ground beetles, earwigs and rove beetles prey on all stages of the pest. Several native parasitic wasps attack this pest. A granulosis virus has also been found infecting caterpillars in the field (diseased caterpillars have a milky white colouration and are sluggish). However, in many cases control is not satisfactory, therefore several parasitic wasps, native from South America, the area of origin of the pest, have been introduced to several countries in Africa. The most important are Copidosoma koehleri and Apanteles subandinus. These wasps have provided effective control of the pests in several countries, particularly in Southern and Eastern Africa
• Use healthy, clean seed, since infested seed tubers are the main cause of re-infestation in the field.
• Avoid planting in rough soil. Plant as deeply as possible (10 cm deep) and ridge at least 3 times during the growing season. Experiments in Sudan showed that increasing the sowing depth from 2.5 cm practised by farmers to 7.6 cm, significantly reduced damage by the cutworms and the potato tuber moth and resulted in an increase of 3.7 t/ha in marketable yield (Siddig, 1987).
• Ensure compact hilling. This is very important to prevent moths reaching the tubers to lay eggs. It also makes it difficult for caterpillars to reach the tubers. In addition, emerging moths from infested tubers will not be able to emerge through deep soil.
• Provide enough water to prevent soil cracks.
• Mulch the plants with rice straw and/or with leaves. Mulching with neem leaves during the last 4 weeks before harvest significantly reduced insect damage in Sudan. (Ali, 1993).
• Intercrop potatoes with hot pepper, onions or peas.
• Harvest the crop immediately as it matures, as tubers left in fields for longer periods are highly infested.
• At harvesting, ensure that the tubers are not exposed to moths before they are properly protected in the store. All harvested tubers have to be bagged and removed before late afternoon every day.
• Destroy all infested potatoes immediately and remove all plant residues from the field. Caterpillars pupate in the tubers and dry stems left in the field.
• Destroy all volunteer potato plants before planting new potato crops.
• Use alternative pesticides to protect potatoes in store.
• Neem can be applied to reduce damage by the potato tuber moth. For instance, in India a four months protection was achieved when harvested potatoes and the covering material were sprayed with five and 10% enriched neem seed extract (Saxena, 1995). In Sudan spraying neem seed and leaf extracts (1 kg/40 l water) and then placing tubers in jute sacks reduced post harvest losses by the potato tuber moth compared with traditional methods such as leaving the tuber unprotected or covering them with banana leaves only (Siddig, 1987). A neem seed extract was also effective for control of the potato tuber moth on stored potatoes in Egypt (Salem, 1991) . Storage loss after 6 months in potatoes treated with 100ppm neem oil was 25% (compared to 10% with the insecticide carbaryl). Adults from larvae treated with neem oil were deformed. Work in Yemen confirmed the beneficial effect of neem; neem oil and sunflower oil halted the development of caterpillars of the potato tuber moth in storage. However, caution is needed since the oil seemed to interfere with potato respiration, leaving the potatoes very soft with dark tissue (Kroschel, 1995).
• A Bt (Bacillus thuringiensis) preparation in powder form mixed with fine sand (1:25) dusted was very effective in controlling this pest in the store in Yemen and Kenya (Kroschel, 1995). Tuber infestation was also reduced by bedding the potatoes in the leaves of the Peruvian pepper tree (Schinus molle), also known as mpilipili in Swahili, and Eucalyptus sp. (Kroschel, 1995).
• Storing potatoes in layers with branches of lantana is recommended by Kenya Institute of Organic Farming (KIOF) in areas where this pest is present lantana is reported to repel tuber moths.
• Application of plenty of wood ash or diatomite earth may also prevent rapid build up of tuber moth.

• Practise proper crop rotation (e.g. potato - brassicas - cereals).
• Use mixed cropping or grow marigolds (Tagetes spp.) or sunn hemp (Crotalaria juncea).
• Maintain high levels of organic matter in the soil (manure and compost).
• Bio-fumigation (incorporating fresh plant mass, especially mustard or radish plants, in large amounts into the soil before planting potatoes) helps against root knot nematodes. Decomposing plant parts release compounds, which kill nematodes. Two weeks after incorporating plant material into the soil a new crop can be planted (phytotoxic effects are exhibited if the crop is planted before 2 weeks).

For more information on Biofumigation click here

• Practise crop rotation.
• In case of scab use healthy certified seed tubers.
• Disinfect seed tubers from infected field through heat-treatment (10 min in water at 55 °C). The same treatment of naturally or artificially contaminated seed tubers gave complete absence of blackleg infection in the field and decreased the amounts of powdery scab (Spongospora subterranea) and black scurf (Rhizoctonia solani) on progeny tubers. For more information on heat treatment click here.
• Avoid excessive liming and continuous cropping with potatoes.
• Maintain soil pH at about 4.8 if continuous cropping cannot be avoided.

• Use virus-free seed tubers.
• Plant resistant varieties where available. In Kenya, the following potato varieties are claimed to possess some resistance to viral diseases: "Kenya Baraka", "Roslin Eburu", "Feldelslohn", "Annet" and "Dutch Robjn".
• Uproot infected plants to reduce the incidence of infection and spread of the disease within a field. For maximum effectiveness remove the diseased plant, the 3 plants on each side of the diseased plant in the same row, and the three closest plants in adjacent rows. This is particularly important in seed fields.
• Control of insect vectors may reduce virus spread.
• Do not overlap potato crops.
• Practise good field sanitation.
• Control nightshades and volunteer potatoes because these plants are reservoirs for viruses

• Practise crop rotation. Rotation of 2 or 3 years is an important strategy to control perennial weeds. Weeds tend to thrive with crops of similar growth requirements as their own and may benefit from practices directed to the crop. When diverse crops are used in a rotation, weed germination and growth cycles are disrupted by variation in cultural practices associated with each crop.
• Control weeds early in the season. It is important to stop broadleaved weeds or annual grasses from appearing above the crop and competing strongly for nutrients and moisture when tubers are enlarging.