Weeds

• According to the University of Wisconsin, weeds significantly disrupt the growth and harvest of peanuts. Hand weeding is necessary to keep weeds under control and allow peanut plants to produce a full ground cover. Mulching and growing peanut plants close together prevents weeds from taking a foothold in the first place.
  
  

Pests

• Leaf-feeder insects cause damage to peanuts by eating above-ground portions of plants, which reduces nut yields, according to Clemson University. Soil-inhabiting insects, such as nematodes, cause trouble by feeding on the nut pods that lie below the soil. Some pesticides are designed for use on peanut plants. Annual crop rotation helps to stop the pest cycle.
  
  

Diseases

• Peanut leaf spot diseases cause brown and black spots on foliage. The infected leaves fall off and complete defoliation is common. Wet foliage often leads to the onset of leaf spot, so ground-level watering that keeps leaves dry is recommended.