Ground Nuts

Growth Environment

• Rainfall of 1,016mm is sufficient for the growth of groundnuts. They require five months of warm weather, and an annual rainfall of 500 to 1000mm or the equivalent in irrigation water.
• The water requirement is greater at flowering, pegging and pod filling.
• Dry weather is required for harvesting and drying.
• The plant cannot tolerate water logging.
• Well drained soils, preferably sandy loams with high Sulphur content and well aerated are required.
• Excessively heavy soils are not suitable.

Planting Material

Seeds are most commonly used. Larger seeds give better emergence and better yields. Maturity depends on the type used, but varies from 90 – 135 days (3 – 4.5 months).

Sowing

• Seedbed should be fine and free of weeds.
• Sowing should be done in wet spells, in the first or second rains, to ensure rapid and even germination.
• Early planting is recommended to reduce the risk of rosette infection which increases as the season advances.
• Row planting at a spacing of 45cm x 15cm for spreading types such as Igola-1; 45cm x10cm for bunch types such as Red Beauty.
• Seeds should be planted 5 – 8 cm deep.
• Seed rate is 20 – 25 kg/acre for spreading types and 25 – 30 kg/acre for bunch types.

Fertilizer requirement

• Farmyard manure applied to the field before planting improves yield.
• Application of 10 – 12 ton per hectare of chicken manure or 20 ton per hectare of well decomposed farmyard manure should be completed at least one month before sowing.
• This should be mixed into the soil for good plant development and to improve soil structure.
• Also, the use of a fertilizer combination of calcium, potassium and magnesium applied as Single Super Phosphate at the rate of 125kg/ha before planting will improve yield because the fertilizers promote nodulation.

Weed Management

• Weeds cause much damage to the groundnut crop during the first 45 days of its growth.
• Early weed control is critically important from 3 – 6 weeks after sowing in order to achieve maximum yields.
• Weeding two or three times is necessary in hand hoed fields.
• Herbicides, if applied judiciously, may be used, for example, round up.
• However, a combination of methods could be more effective and economical.

Harvesting

• Premature harvesting of groundnut pod slows the yield, oil percentage and quality of seeds.
• Harvest when the plants have shed their leaves and when the inside of the pod turns dark brown.
• Leave the groundnuts in windrows for 3 days before plucking.
• Harvested plants should be stacked in the field for a few days for air and sun drying before stripping the pods.
• Clean the pods by removing the soil and other dirt and dry properly before storing in a well ventilated place.
• Delay in harvesting after physiological maturity can result in increased Aspergillus flavus infection, and aflatoxin contamination in pods/seeds, and many pods may be left in the soil due to weakening of pegs.

Yield

Yield of local varieties range between 600 – 1000kg/ha with a national average of 800 kg/ha. With good husbandry, improved varieties can yield up to 3,500 kg/ha for example Igola-1 yields 3000 -3500 kg/ha, Red Beauty 1,900 – 2,500 kg/ha, Roxo 2,000 – 2,700 kg/ha, Igola-2 2,500 kg/ha and Serere Red 2,500 – 3,500 kg/ha.

Crop Rotation

• A crop rotation of groundnut-cereal-cereal helps in efficient nutrient utilization and reduces soil borne diseases and nematodes.
• It also helps to reduce the incidence of weeds.
• Maize, sorghum, pearl millet or small grain crops can be grown following groundnuts.
• To reduce the incidence of soil borne diseases, it is recommended not to grow groundnut after tobacco or cotton.

Field Pests

Groundnuts Aphids

• These spread the groundnut rosette disease which in severe cases may cause up to 100% damage.
• The pests should be sprayed with menazon, endosulfan and phosphamidon.
• Thrips, potato leaf hoppers and bollworms also attack groundnuts and can be controlled in a similar manner to the aphids. Sprays should be directed towards the base of the plant.

Leaf miner

• Groundnut leaf miner is a very serious pest of groundnuts attacking in both the rainy and post rainy season crops is regarded as the most important pest threatening groundnut production whenever outbreaks occur.
• It is more damaging during the short rainy cycle when long drought precedes rains.
• In Uganda, total crop losses have been reported by some farmers.
• No resistant variety is yet available in Uganda through tolerant variety Serenut 10R was released in 2011.
• Leaf miner larvae mine the leaves and feed inside the leaflets. Eggs are singly on the underside of the leaves of groundnut, soybean and other leguminous plants.
• Young larvae mine the leaves and later instars exit the mine to web together several leaflets.
• Damaged leaves become brownish, rolled and dissected which results in early defoliation and affects the growth and yield of the crop.

Control methods

• Spraying with Monochrotophos 36SL at 600ml/ha or Dimethoate 30 EC at 650ml/hha in 600l water.
• Growing groundnut-cereal rotation reduces the leaf miner incidence
• Growing resistant genotypes such as Serenut 10R

Storage Pests

Peanut bruchid beetle

Groundnut bruchid caryedon serratus is also known as peanut bruchid beetle, groundnut borer, seed beetle is a serious pest of stored groundnuts, particularly when these are still in their shells.

The damage caused is particularly significant when the groundnuts are desired for confectionary purposes.

The translucent milky-white eggs are attached to the pod wall.

After hatching, the larva burrows straight through the egg shell and the pod wall, and start eating the seed.

The first sign of attack is the appearance of ‘windows’ cut into the pod wall by the larva to allow the adult to leave the pod after emerging from the pupal cocoon.

Fully grown larvae sometimes come out through the exit holes made by the previous generations.

Treatment and Control

• To prevent primary infestation from alternative hosts (Tamarind, Acacia, and Pongamia) avoid drying groundnuts near these host trees.

Red Flour Beetle

• Fumigate with methy 1 bromide 4 followed by chlorpyriphos at 3-g/kg seed.

Groundnut Rosette Disease

• This virus is the most serious disease. It is spread by aphids.
• The groundnuts should be sprayed with Rogor (Dimethoate) two weeks after emergence and at 10 day intervals for a total of 4 times.
• Use of resistant types such as Igola-1 eliminates costs on chemicals.
• Recommended spacing must be followed because wide spacing increases disease incidents.

Leaf Spots Disease

• Cercospora leaf spots should be sprayed with Dithane M-45, Benlate and Brestan.
• Crop rotation should be practiced and crop debris should be burnt.

Root and Stem wilt also affect the crop. The control can be achieved by crop rotation, use of clean planting materials and burning of crop debris.