What are the common pests and diseases that could affect soybean production?

Category: Bacterial

• Bacterial blight Pseudomonas syringae. Symptom: Water-soaked spots on leaves which enlarge and become necrotic; spots may be surrounded by a zone of yellow discoloration; lesions coalesce and give the plant a burned appearance; leaves that die remain attached to plant; circular, sunken, red-brown lesion may be present on pods; pod lesions may ooze during humid conditions.

• Bacterial pustule Xanthomonas campestris. Symptom: Tiny pale green spots with raised centers on both upper and lower leaf surfaces which develop raised pustules in lesion center; pustules usually form in lesions on lower leaf surface; mottled brown areas may develop on leaves if lesions coalesce; small red-brown spots may develop on pods of some varieties.

Category : Fungal

• Rhizoctonia stem rot Rhizoctonia solani. Symptom: Damping-off (pre-or post-emergence death) of seedlings caused by red-brown lesions which girdle the stem; lesions or cankers may be present on the stem of older plants and cause the death of the plant mid-season.

• Rust Phakopsora pachyrhizi. Symptom: Gray or red-brown water-soaked spots on leaves which turn are tan to dark reddish-brown in color lesions may also be present on stems, petioles, and pods; volcano-shaped uredinia (spore-producing structures) are present within the lesions; plants drop leaves and mature prematurely.

Category: Insects

• Armyworms (Beet armyworm, Western striped armyworm). Symptoms: Singular, or closely grouped circular to irregularly shaped holes in foliage; heavy feeding by young larvae leads to skeletonized leaves; shallow, dry wounds on fruit; egg clusters of 50-150 eggs may be present on the leaves; egg clusters are covered in a whitish scale which gives the cluster a cottony or fuzzy appearance; young larvae are pale green to yellow in color while older larvae are generally darker green with a dark and light line running along the side of their body and a pink or yellow underside.

• Cucumber beetles (Western striped cucumber beetle, Western spotted cucumber beetle). Symptoms: Stunted seedling; damaged leaves, stems and/or petioles; reduced plant stand; plants may exhibit symptoms of bacterial wilt; scars on fruit caused by beetle feeding damage; adult beetles are brightly colored with either a green-yellow background and black spots or alternating black and yellow stripe.

Source: Soybean