How To Grow Potatoes In Zimbabwe

How To Grow Potatoes In Zimbabwe

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Below are How To Grow Potatoes In Zimbabwe

Soil and Site Selection for Growing Potatoes

The best site for potatoes has full sun (6-8 hours of sun) and well-drained soils. Potatoes can be grown in most soil types but prefer loose, well-drained sandy soils with good aeration. Avoid heavy clay soils. Potatoes will rot in poorly drained soil or heavy clay soils.

The best soil pH for potatoes is between 5.0 and 6.5. It helps if the soil is fertile and moisture retentive, so apply a thick layer of compost prior to planting. A high soil pH (alkaline) is not suitable for potatoes because it can cause scab disease. Your soil test will give you your soil’s pH.

Practice a three-year crop rotation in your fields. To do this change the field which you grow your potatoes, compost and or potato family plants each year. Only plant again in that same field once every three years. It helps control and prevents insects and diseases. Potato-family members (Solanaceae) including tomatoes, peppers, tobacco and eggplants.
Without crop rotation, your potato losses can go up as high as 30% due to soilborne diseases. The best rotational crops for potatoes are cereals (wheat or maize) and forage grasses (Rhodes grass, Katambora).

Don’t bother growing potatoes in containers such as sacks or tyres. The yields will be dismal and will not make a good return on your investment. Stick to the fields!

The potato can be grown in warm or cool climates. However, it does not withstand frost well. Frost can drastically reduce your potato yields. If frost is likely after the leaves of your early potatoes come up, cover them with floating row cover, straw, newspapers or dirt. It is better though to plant after frost danger has passed.

Potatoes also can’t take a lot of heat, and tuber development is affected by high temperatures (above 30 degrees C).

The main potato growing period in Zimbabwe is in late winter (2nd winter): from late July to early August after the last frost. Planting times vary depending on your area.

Summer crops: are planted in November before the rainy season. These are more prone to disease pressure but get good germination.

1st winter: are potatoes areplanted between February and April. They mature before frost begins. In the Lowveld areas, better to plant later. Plants are susceptible to late blight. Choose blight resistant varieties.

Land Preparation

Land preparation to grow potatoes is typically done using machinery to speed up the process. Plough the soil using a chisel plough or subsoiler to a depth of about 20-25cm, to a fine tilth. 

You can also use a hand-held digger or a rotary tiller for working your soil before planting. It may take a little more time and energy. But can be better for your soil structure.

Do not till the soil when it is wet.

Follow through with a disc harrow to disc dead weeds. It takes many passes to get your soil to the ideal state for planting and good tuber development. Look into renting farm equipment and factor in equipment rental and fuel costs into your overall costs.

The next step is to make straight ridges using a potato ridger to set up ridges. Ridges should be between 75-90cm wide.

Amend your beds with compost and manure. Evenly mix in 25-30t/ha of well-rotter organic matter (compost or manure). Organic matter is critical for improving your soil’s water holding capacity, texture, tilth and nutrients.

Sowing and Planting Potatoes

Sow sprouted tubers (potato seeds) into the ridges at a planting depth of 10-15cm right way up with eyes (or chits) facing upward.  Plant deeper for dryland cultivation.

You can sow by hand or machine.

The ideal spacing for your potato seed is  20 or 30cm apart within rows (intra-row). Inter- row distance is75 or 90 cm. Seed size and soil fertility affect row spacing.

Spacing your  plants far enough apart in the rows will give them enough room to thrive. Crowding them can cause reduced fruit yield, size, and quality.

Cover over the tubers with a least 2.5 cm of soil using a rake.

It takes about 10-15 days for plants to germinate. Days to maturity range from 80 to 140 days.

As the shoots emerge and reach about 4-6 inches tall, mound the soil to cover most of the leaves. This is a process known as hilling. Hilling up (or ridging) soil around young potato plants increases yield, loosens soil and prevents weeds. It also prevents tubers from greening and getting a bitter taste.

Three weeks later, ridge (hill) again and top dress.

Plant Management

Fertilising Your Potatoes

A soil test is effective for a good fertilisation strategy. Apply fertiliser requirements based on your soil analysis results.  You can get information on testing from Kutsaga or your nearest research centre.

Potatoes respond well to organic matter. Provide them with well-rotted compost or manure to amend your soil. Rake in 30t/ha of well-rotted manure evenly over the bed. Using compost and soil amendments can help you reduce your fertiliser costs.

Potatoes need plenty of nitrogen. Manure and compost are also good sources of nitrogen. Nitrogen is important for the overall development of the plant stems and leaves.  Signs of nitrogen deficiency are slow growth, stunting and smaller than normal potato leaves.

Weigh out and apply a compound balanced fertiliser at the time of planting at about 170g per square metre.  Dig a furrow alongside the planting row and add moisture. According to the FAO, basal fertiliser (Compound C) or (Compound S) recommendation is about 1000kg/ha. But it really depends on your soil analysis, soil type and the climate condition.

Do not overuse nitrogen, though, stick with the recommended quantities. Plants with too much nitrogen are far too lush, green and have little or no fruit.

Top dress (add fertiliser after the plants are growing) with potassium nitrate around your plants at 4, 8 and 12 weeks. Potassium improves the tuber quality (size, starch content, and storability). Do not put fertiliser on plants it can scorch foliage, put it around plants.

Add Ammonium Nitrate (AN) at 290 kg/ha three weeks after emergence.

Top dress with Sulphate of Potash split into two applications first at flowering and then two weeks after flowering.

Weeding
Keep the soil free of weeds to ensure high yields.Weeding is easier with potatoes because of hilling. Potatoes have shallow roots, so be careful not to damage them with a hoe when you are hand weeding.

Remove weeds early and often before they flower and set seed. Young weeds are also the easiest to remove.

Tips for controlling weeds:

• Manually weed using hand fork or hoe.  Then leave weeds in the sun to dry before discarding.
• Mulch with straw or compost to help suppress and control weeds.
• Solarize your soil before planting. You solarize by trapping the heat of the sun using plastic and raise soil temperature to  by several degrees, thereby killing weed seeds, roots, and bulbs.
• Use pre-and post-emergence herbicides (such as Topogard, Senco) if weeds are excessive.

Watering Your Potatoes
Water is important for potato farming, so plan to set up irrigation early.  Potatoes are shallow rooted and need ample amounts of water during tuber set and full growth.

Here are the stages of potato development: i) sprout development , ii) vegetative growth, iii) tuber initiation, iv) tuber bulking and v) maturation.

Keep the soil moist, but not wet using furrow, drip or sprinkler irrigation.  Drip irrigation is the best because it saves time, water use and effort. Provide extra water for early potatoes during dry conditions.

Potatoes are sensitive to drought. Water deficits during critical periods such as tuber development cause low yields and small tubers. If the soil dries after tuber development, the second growth will result in knobby potatoes. Dry conditions can cause hollow heart in potatoes.

Good watering tips:

• Water in the early morning or in the evening
• Do not water during the hot period of the day, it leads to evaporation
• Use soil moisture sensors and rain gauge to monitor water
• End irrigation about 10 days before harvesting.
• Don’t overwater

Problems, Pests, and Disease

The potato is often the victim of several pests and diseases which can cause crop losses if not properly managed. Minimize the chances of disease by planting disease-resistant seed potato varieties and rotating crops to a new field each year.

Potatoes are susceptible to a number of common pests including aphids, Colorado potato beetles, and blight. Make it a point to monitor, detect and identify insect damage early.
Pests
Aphids:  If the foliage on your plant curls, puckers or turns yellow it is a sign of aphids.  Aphids are tiny green, brown or pinkish insects that appear on the undersides of leaves. Serious threat to young plants.
Control: you can attract beneficial bugs such as ladybugs and wasps to eat aphids. Other solutions are blasting with a hose, pyrethrin, and  neem. Chemical control: Thionex, Azodrin

Nematodes: They are whitish, translucent worms, barely visible. They live in the soil and attack plant roots. Signs of nematodes are stunted plants, with yellow leaves.
Control: choose, resistant varieties, rotate fields with grasses, use compost and use sticky traps to detect and solarize the soil to prevent nematodes.
Tuber worm: if you find that your potatoes have tunnels it is a sign of potato tuber worms.
Solution: weed, sanitize your tools, hand pick pests.
Potato Tuber Moth: larvae that make tunnels in the plant, wilts and die.
Solution: ridge plants. Chemical control: Azodrin or Novacron.
Potato Leafhopper: Leafhoppers pierce leaves, buds and stem making potato plants weak. They put small white specks freckle leaves and leaf edges turn brown.
Control: Use pyrethrum, neem, weed and sanitize fields after harvest.

Flea Beetle: If you find several holes or perforations in the leaves of your plants, the plants may have flea beetles. Flea beetles are long, shiny and black with yellow or white markings.
Control: rotate your crops, use sulfur, neem. Apply 2 applications of pyrethrum 3 to 4 days apart.
Colorado Potato Beetle: defoliated plants and skeletonized leaves are signs of the Colorado beetle.
Control:you can hand pick them off your plants. Encourage beneficial bugs. Use row covers or neem.
Disease (viral, fungal and bacterial)

Early Blight: also known as leaf spot.Signs are circular and irregular dark spots that develop on older leaves. The spots have yellow halos.
Control:  Manage water, mulch, weed. Chemical control: Apply fungicides (Ridomil , Dithane)  every 7-10 days according to directions.

Late Blight: occurs when relative humidity is above 70% and temperature 22-25 degrees C. Spreads quickly in wet season. Signs: purple or brown-black areas on the blade of leaf or leaf stalk. Fruits will have large greasy brown spots.
Control: hill the rows to help prevent spores getting to the tubers. Remove all infected foliage at once and discard it, don’t compost it.

Potato Scab: areas of the surface becomes brown, roughened. Caused by soils with high pH and that are dry. Unsightly but still the potato is still edible.
Control: Manage water, improve drainage, weed, mulch and don’t lime.

Blackleg: a bacterial disease that causes stunting, wilting of plants and decrease in yield. It thrives in wet conditions. Signs are blackening and decay of lower stem.
Fusarium Wilt: causes yellow foliage, brown discolouration and wilting of leaves and stems.
Verticulum Wilt: later in the season leaves infected with verticillium wilt become yellow and die.
Control: apply a sulphur fungicide every 7 to 10 days once the symptoms have been found.

Leafminers: silvery gray trails loop through the leaves. Headless, legless, whitish maggots inside the leaves. The adult insect is a fly.
Control: weeding, rotating your crops, using pyrethrin, neem, and encouraging beneficial insects.

Prevention practices are most the effective (cost and effort) in the long run.
Pest Control Tips

• Add organic matter (well-rotted compost/manure) to soil
• Keep weeds under control
• Plant disease-free tubers
• Choose disease resistant varieties
• Rotate your crops
• Use mulch
• Irrigate well
• Remove and destroy infected plants
• Use pre-and-post emergence herbicides and fungicides
• Hand-pick large pests
• Sanitize tools
• Solarize soil using clear plastic to destroy harmful agents.
• Use sticky traps for early pest detection and monitoring
• Use beneficial insect predators to attack pests
• Remove plants from fields at the end of the season and keep field clean 
• Use agricultural fleece

Using Chemical Controls: 

If spraying does become necessary only use a chemical that is specific against the particular pest involved and use it strictly in line with the manufacturer’s instructions.  Never spray a chemical without knowing what it’s for and properly identifying the pest. Chaos spraying can damage crops.

Choose the weakest chemical if it can do the job. You can buy insecticides, pesticides and herbicides from Windmill or ZFC.

Tips for good use of chemicals

• Fully read directions before you spray
• Wear protective clothing
• Mix chemicals in well-ventilated room
• Choose cool, dry day to spray
• Wash your hands and face after using chemicals
• Store chemicals out of the reach of children
• Do not overdose, it does not help.

Harvesting & Storing Potatoes

Harvesting
Correct harvesting and timing are important. You can hand-dig and harvest using garden forks or a mechanical lifter (potato harvester) to unearth the entire plant. Harvest crops once 95% of the foliage begin to die down.  To facilitate harvesting remove potato haulms two weeks before harvesting. It can help firm the potato skins for storage. Harvest in the morning during dry periods.

Be careful when harvesting to avoid bruising, skinning or cutting your tubers.

Leave the potatoes on the surface of the soil for at least a few hours to dry their skins. In hot conditions put them in a sheltered place to avoid a drop in quality.

Sort and grade potatoes (by size, colour, texture). Remove and discard any rotten or infected tubers before storing.

The average yields for potatoes in Zimbabwe are 17-20t/ha in summer and 25-40t/ha in winter. According to the International Potato Center, attainable potato yields can be as high as 35t/ha with good farm management.

Storage

Good storage is important for maintaining the tuber quality before marketing. Store your potatoes in ambient temperature in the cool, dark and well-ventilated building. Good storage prevents dehydration, sprouting and bruising.

It is important that tubers are protected from light or they will go green and become toxic. Use light only when very necessary.

Store potatoes dirty at between 3 – 5 degrees C. You can store in pallets for short periods of about 4-5 months. Long term pallet storage is not recommended due to poor air circulation. Well stored potatoes can be stored for up to 6 months or more.

Marketing

You need to make plans for marketing before you plant. Make arrangements for your transport to market too. If you can coordinate marketing with other farmers consider it. It could reduce your marketing and transportation costs.

Be careful when transporting your potatoes. Your potatoes can be damaged during transportation due to mishandling. Make sure you monitor how your potatoes are handled. Don’t stop your diligence now, you have come too far!

Package your potatoes in the right containers depending on your market. Most potatoes sold on the fresh market are sold in 15kg pockets.
Consumption trends: There is an increasing demand for potatoes in urban areas from the growing number of fast food outlets and restaurants. More consumers are diversifying their eating habits and eating more chips (french fries). Demand for potatoes is affected by price. If they are too expensive consumers will buy less and substitute them for a cheaper option.

Selling to the fresh market: deliver clean, quality potatoes to the fresh market (informal markets). You need to remember that  you are competing with imports from South Africa that are of higher quality and are clean, which most customers prefer.

The prices of fresh potatoes at the fresh market is affected by supply and demand. This fluctuates which makes potato prices largely unstable.

The Agricultural Marketing Authority provides a weekly update on market prices. Check it for historic prices of potatoes and to keep track of current market prices. If prices are low, which they typically are at harvest time, store your potatoes to sell them later when prices increase. If you can afford to wait.

You can find fresh agricultural markets are in urban areas around the country. Mbare Musika being the largest.

Selling to processors: you can sell chipping potatoes to processors who process them into chips, crisps or dehydrate them. Processors typically contract for the majority of their expected requirements prior to production. You may need to produce high yields, have a large area under production and a fair contract for it to be profitable. A good contract can help you with inputs, production support, and guaranteed market. Processors include Cairns and Interfresh.

Selling to anchor farm: If you are close to a large farm or farming company you can supply it as an outgrower.Some small farmers can supply Tanganda as potato outgrowers.

Selling to supermarkets: when selling to supermarkets or wholesalers you need to understand the quantities required, payment terms and quality requirements. Some supermarkets may require you to grade, wash, sort and package your potatoes before you supply them. Some supermarkets you can supply include Pick n Pay, Fruit and Veg City, TM etc.

Exporting: to Mozambique is a possibility if you are a farmer in the Eastern Highlands. You will likely need to coordinate marketing efforts with other potato farmers to make it possible.
Producing seed potatoes for other farmers: growing certified seed potato especially for farmers in areas with suitable climatic conditions and access to water offers a great opportunity with good returns. It also helps decrease the cost of production for other farmers.

Bottom Line for Potatoes

Overall cost: $4,500 to $6,500 per hectare
Price: $12 large, $10 medium, $9 small pockets
Average Yield: 17-20t/ha during Summer; 24-28t/ha in Winter
Potential: 35t/ha

Potato Financials Include:

• Soil test
• Land preparation
• Seed potato
• Potato blend fertiliser
• Gypsum
• Top Dressing
• Chemicals (fungicides, sprayer, insecticides, and herbicides)
• Labour (weeding, planting, harvesting and sorting)
• Field Machinery costs
• Packaging