Groundnuts

The objectives of field preparation are based on the following principles: Elimination and control of undesirable plants like crop volunteers and weeds to reduce competition with the established main crop;

• Provide favorable conditions for sowing, allowing germination, emergence and good plant development;
• Maintenance of fertility and productivity over the long term by preserving the soil organic matter and avoiding erosion;
• Breaking of hard pans or compacted layers to increase water infiltration through the soil whilst avoiding erosion;
• Facilitating mixing of fertilizers, lime, or agro-chemical products into the soil;
• Incorporation of organic and agricultural residues.
• Tillage operations should be repeated when the weed seeds are just germinated.
• When the soils are heavily infested with perennial weeds like Cynodon or Cyperus, deep ploughing is needed.

Planting date: Mid October- mid-November

Seeds coating: seeds of groundnuts are susceptible to fungal rot in the soil. It is, therefore, recommended to  treat seeds with Mencozeb  and Thiram products. Comprehensive directions of use are  indicated on the label.

Spacing: 50 cm between the row and 5-10 cm on the row. Seeds are planted in 5-7.5 cm deep hole and covered with the soil

Fertilizer application

Groundnut being a legume crop meets mostly its nitrogen requirement through fixation of nitrogen in the atmosphere. So, groundnut may not respond to large application of nitrogen fertilizers. Excess of nitrogen results in too much of vegetative growth at the expense of groundnut pod production.

However, in early stages of plant growth nitrogen is very much in demand when the plants are in the initial stages of nitrogen fixation. A good strategy for nitrogen management in groundnut cultivation is to apply a starter dose of 15 to 20 kg N/ha, and encourage nitrogen fixation by Rhizobia inoculation to meet the nitrogen needs of plants. The starter dose of nitrogen is side dressed along with phosphorus and potassium application just before sowing. Farm yard manure at 15Tons per hectare is enough to provide needed nutrients.

Weeding:  weeds compete with the crop for moisture, nutrients, light and space. Weed to remove all unwanted weeds.

Fertilizer application: If the nodulation and nitrogen fixation is low or poor, then the crop need to be applied with 30 to 40 kg N/ha after 30 to 45 days of sowing.

The top-dressing should be done at proper moisture level in soil followed by intercultivation or manual weeding. Lime application is essential to grow groundnut in acid soils. … Apply well powdered gypsum at 250 kg/ha close to the base of plants at 20-25 days after sowing on either side and incorporate in the soil, so that it remains in top 3 cm of soil.

Rotation: rotate groundnuts with non-legume crops to prevent and avoid diseases.

Groundnut crop is infested with sucking type of insects pests like aphids, leaf minor thrips, leaf eating caterpillars, leaf webber, etc in the initial and active growth stages. In the later stages, the crop may be attacked by pests like Groundnut earwig or pod borer which punc­tures the developing pods causing heavy damage.

6. 1. Cercospora arachidicola is a fungal ascomycete plant pathogen that causes early leaf spot of peanut. All cultivars of peanuts are equally susceptible to peanut fungal pathogens; however, C. arachidicola is an economically important peanut pathogen and is responsible for significant economic losses in the peanut industry, more specifically in the Southeastern, Eastern, and the Southwestern United States. Early leaf spot of peanut can drastically reduce yields, leading to economic downturn of the peanut crop economy. Annual crop losses in the United States range anywhere from less than 1% to greater than 50% depending on disease management and treatment.

Symptoms

Cercospora arachidicola only infects peanut plants, causing symptoms of brown lesions with chlorotic rings on the stems, leaves, and petioles. The first macroscopic symptoms usually appear on the adaxial surface of the lower leaves about 30 to 50 days after planting. Further damage can lead to premature defoliation and even yield loss. Signs include tufts of silvery, hair-like spores on lesions during humid weather.

Control

Early leaf spot of peanut can be treated through:

•  the use of fungicides such as chlorothalonil,  Tebuconazole, Pyraclostrobin applied at the very early pod stage, and applied every two weeks thereafter.
• Following the severity and incidence of the infection, strip-tillage techniques have also proven to be effective in delaying an epidemic by reducing the amount of initial infection.
• Use of resistant cultivars is the most successful way to be overcome the pathogen and maintain yields\

Ibimenyetso by’indwara y’ibidomo by’ikigina ku mababi y’ubunyobwa

2. Groundnut rosette virus (GRV) is a peanut pathogenic virus found in Sub-Saharan Africa. It is transmitted between plants by insect vectors such as the ground aphid (Aphis craccivora).

Groundnut rosette virus was first described in Africa in 1907 and causes serious damage to groundnut crops on that continent. In 1939 it was reported to infect 80 to 90% of plants in the Belgian Congo causing major losses in yield. The virus can spread rapidly through a crop.

Groundnut infected by Rosette disease

Control:

• Use resistant varieties,
• Use the same measures as the control of aphids.

3. Ground nut Aphid: Aphis craccivora  Koch.

Ground nut aphid injects a powerful toxin into the plant while feeding and, when populations are large, this can stunt or kill plants. While feeding, this aphid produces a considerable amount of honeydew upon which sooty mold grows. The black sooty mold reduces photosynthesis and may make leaves unpalatable to livestock. Damage symptoms include yellowing, wilting, and dieback. In general, legumes can be seriously damaged, either by direct insect feeding or by the transmission of virus diseases (Rossette & Peanut strip virus.)

Control

• inella septumpunctata,Menochilus sexmaculatus & Chrysoperla carnea keeps the pest under check. ( if 1  predator per plant no need of insecticide application.).
• Grow cowepea and Ground nut together..
• Phosphamidon 0.03 %
• M-O-D 0.025 %
• Dimethoate 0.03 %

4. Thrips: (Scirtothrips dorsalis, Thrips palmi)

Nymphs and adults lacerate the surface of the leaflets and suck the oozing sap resulting in white patches on lower surface of the leaves and distortion of young leaflets. Severe infestations cause stunted plants.

Cultural Control

• Grow tolerant varieties,
• Uproot and destroy severely infected plants,
• Conserve bio agents like flower bugs (anthocorids), lady bird beetles (coccinellids), praying mantis, green lace wing (chrysopids), long horned grass hoppers, dragon flies and spiders’
• Spray Monochrotophos 36SL 600 ml/ha or Dimethoate 30 EC 650ml/ha or Methyldemeton 25 EC 600 ml in 600 liters of water.
• Spray per acre monocrotophos 320ml mixed with neem oil 1liter and 1kg soap powder mixed in 200 liters of water twice at 10days interval.

5. Leaf miner Aproaerema modicella

Nature of damage
Small blister like mines are seen on the upper leaf surface near mid rib. As the feeding advances, the mines increase in size and the entire leaflet becomes brown, rolls, shrivels and dries up. In severe cases the affected crop presents a burnt up appearance. Later stages larvae web the leaflets together and feed on them, remaining within the folds.

Control:

• The adult moths are attracted to light from 6.30 to 10.30 P.M. Petromax lamp placed at ground level attracts moths
• Crop rotation with non-leguminous crops would considerably reduce the leaf miner population.
•  Rotation of groundnut with soybean and other leguminous crops should be avoided.
• The most promising method of control would be utilization of resistant/tolerant varieties.

•  Monocrotophos 0.04 %, DDVP 0.05 %, Fenitrothion 0.05 %, Endosulfan 0.07 %, Carbaryl 0.2 %, Quinalphos 0.05 %.

6. Pod borer: Helicoverpa armigera      

Damage

Larvae feed on the foliage, prefers flowers and buds. When tender leaf buds are eaten symmetrical holes or cuttings can be seen upon unfolding of leaflets.

Cultural Control

• Deep summer ploughing
• Intercrop one row of red gram for every 5 or 6 rows
• Install pheromone trap @ 5/ha
• Crop rotation with sorghum, maize, pearl millet and sugarcane minimizes the infestation.

7. Ground nut White grub: Holotrichia consanguinea

Adults are 18-20 mm long and 7-9 mm wide. The eggs are white, almost round. The young grubs are translucent, white and 5 mm long. Beetles emerge out of the soil within 3-4 days after the onset of rain.  Install light traps with the onset of rains and count the number of beetles per day. Dig 100 X 100 X 20 cm pit @ 10 pits per ha, collect and count the number of beetles per pit.

Both adults and larvae are damaging stage.The larvae feeds roots and damage pods. Grubs feed on fine rootlets, resulting in pale, wilted plants dying in patches.

Mechanical Control

Collection and destruction of white grub adults from host trees around the field. In areas where white grub is persistent problem, deep ploughing after harvesting the crop can reduce the population as birds can pickup the grubs, and destruction of pupae.

 Control

• Apply safe chemical insecticides at recommended doses only if the insect population crosses the ETL.
• Control white grub adults by spraying their feeding trees like neem etc. with Carbaryl 50 WP at 2 g per liter of water. OR Chlorpyriphos 20 EC @ 2 ml/lit of water soon after first monsoon showers for 3-4 days in the late evening hours kills the adult beetles and reduces root grub infestation. This spraying need to be repeated 3 to 4 times until mid-July, ideally using community approach.
• Application of Carbofuran at 1 kg a.i./ha in the seed furrows can be effective prophylactic measure.
• Seed treatment with chlorpyriphos 20 EC ( 6.5 to 12.5 ml/kg seed) is found effective.
• In case of severe infestation apply phorate 10 G @ 10 kg/ha.

8. Termite

   

Termites are white translucent ant like insects. They enter the root system and burrow inside the root and stem; this usually kills the plant. They bore holes in the pods and damage the seed. They remove the soft corky tissue from between the veins of the pods (scarified). They do not usually damage the seed. But scarified pods are more susceptible to infestation by Aspergillus fungus, which produces health hazard aflatoxins.

Management

• Destroy termite nests by clean cultivation.
• Seed treatment with Chlorpyriphos.
• Drenching of termite nests with Chlorpyriphos solution.
• Application of Carbofuran or Chlorpyriphos to the soil using 1 kg a.i. /ha at planting time can reduce termite incidence.

9. Millipedes (Peridontopyge spp.)

Millipedes are among the economically important soil pest of groundnuts. They are brown to blackish in colour and curl when disturbed. They attack groundnut seedlings, between planting and approximately 20 days after planting, feeding on the emerging cotyledons and moving to the root system at the collar region. The cortex is often damaged serving as an entry point for secondary infection by microorganisms. The development of plants surviving the attack is often retarded.

Millipedes also attack maturing groundnut during pod formation, i.e. when the pods are still soft. Immature pods from severed pegs are often perforated and thus suffer secondary infection or invasion by rot-causing organisms such as Aspergillus flavus. Millipedes may also damage flowers.

Control: Practice good sanitation. Prepare land properly. Select sites away from forest (breeding sites for millipedes). Cover exposed pods. Close cracks in the soil. Use varieties with pods well buried

The groundnut plant usually gives an indication of when to harvest. They should be harvested when approximately 75 % of the pods  have reached the maturity; that is when the leaves turn to yellow colour and dry at the tips. At the same time, the soil desiccate to such an extent that the plant withers and the seeds in the pods begin to thrivel and take on a ripe appearance.

Loosen the soil around the plants with a spade or garden fork before harvesting peanuts. Pull up the plants and shake the excess soil from the roots, leaving the pods attached. Check the soil to make sure you aren’t leaving any pods behind.

After the harvest, groundnuts pods are dried on the sun and, then, threshed and winnowed. Thereafter, groundnuts are sorted (Sorting aims at separating fully filled grains and unfilled or damaged ones and stored. Groundnuts are used in soups, vegetables or roasted and eaten as finger food. In addition, groundnuts are processed into various products such as cooking oil, peanut butter, …