Peas:Diagnostics

PEA PESTS AND NUTRITIONAL DISORDERS

ALTERNARIA BLIGHT (ALTERNARIA ALTERNATA)

‘‘‘Alternaria Blight (Alternaria alternata) ‘‘‘ This disease is characterized by oval lesions that are located on the stipules. These lesions have centrally located rings and have a tannish brown color. This brown color fades to pale green as the disease spreads from the center of the infection to the healthy tissues of the plant. At this time, there are no resistant cultivars available. (Leaf Diseases Caused By Fungi)

ANTHRACNOSE (COLLETOTRICHUM PISI)

‘‘‘Anthracnose (Colletotrichum pisi) ‘‘‘ This disease is characterized by lesions that can be found on all aboveground parts of the plant. Lesions that are found on the leaves are irregularly oval, gray to tan in the center, and brown at the margin. Lesions founds on the pods are circular, sunken, light red in the center, and reddish brown at the margins. The best form of control is use of disease-free seed and good rotation practices in the field. (Leaf Diseases Caused By Fungi)

APHANOMYCES ROOT ROT (APHANOMYCES EUTEICHES)

‘‘‘Aphanomyces Root Rot (Aphanomyces euteiches) ‘‘‘ This disease is characterized by firm, straw-colored lesions that are found on the roots. These lesions spread through the cortex and eventually develop a discolored root system. The disease can be visible one to two weeks after the infection occurs. The best form of control is to check fielding before planting and avoid infested fields. There are no resistant cultivars available for control at this time. (Root Diseases Caused By Fungi)

BACTERIAL BLIGHT (PSEUDOMONAS SYRINGAE PV PISI)

‘‘‘Bacterial Blight (Pseudomonas syringae pv pisi) ‘‘‘ This disease is characterized by lesions that are initially located at the nodes and become particularly populous on the stipules. The lesions begin as shiny spots becoming darker and finally developing as dead areas. As these lesions spread to the leaves, they are water-soaked on the undersides and dark green or brown on the upper surface. Bacterial blight lesions affect all aboveground plant parts which makes it detectable to the naked eye. The best form of control is to use resistant cultivars. In addition, planting seeds in arid areas, avoiding sprinkler irrigation, and staying away from infected fields will also decrease the possibility of developing infection. (Diseases Caused by Bacteria)

BEAN (PEA) LEAF ROLL (BLRV)

‘‘‘Bean (Pea) Leaf Roll (BLRV) ‘‘‘ This disease is characterized by plants that are suffering from severe stunting and often die before they bloom. As the disease progresses and matures, the stunting will continue and the plant may experience yellowing of the entire plant and sudden collapse leading to death. The best form of control is to use resistant cultivars. (Diseases Caused By Viruses)

BLACK LEAF (FUSICLADIUM PISICOLA)

‘‘‘Black Leaf (Fusicladium pisicola) ‘‘‘ This disease is characterized by small, white areas on the undersides of the leaves which develop into spots that grow on the upper leaves as well. The most obvious symptoms are black, elongated lesions that streak the leaves. As the disease matures, the lesions become tan in the center and then darken from tan to gray to black in concentric rings as they grow. (Leaf Diseases Caused By Fungi)

BORON TOXICITY

‘‘‘Boron Toxicity: ‘‘‘ This disease is characterized by plants that are stunted and the first leaves to bloom will have yellow margins. As the disease progresses, the leaves will take on scattered, water-soaked spots that have an olive color along the margins. These areas will eventually dry up and die. Boron toxicity frequently occurs when peas are planted in areas where beets were produced the previous year.. The best form of control is to be aware of the field conditions when a new crop is planted and avoid soil that received a high amount of boron the previous year. (Nutritional Disorder)

BROWN SPOT (PSEUDOMONAS SYRINGAE PV SYRINGAE)

‘‘‘Brown Spot (Pseudomonas syringae pv syringae) ‘‘‘ This disease is characterized by water-soaked lesions that can be seen on leaves, petioles, and stems. Soon after the plant has become infected, the lesions develop a tan color, loses its shiny appearance, and appears burned. The best forms of control is to plant clean seed in arid areas, clean farm and seed-processing equipment between seed lots, and avoid fall planting which may injure the plant from from unfavorable weather conditions. Some resistant cultivars are available and should be used. (Diseases Caused by Bacteria)

CALCIUM DEFICIENCY

‘‘‘Calcium Deficiency: ‘‘‘ Plants suffering from calcium deficiency have very small, red, slightly sunken areas near the leaf midribs. There is no control other than properly fertilizing the soil before the peas are planted. (Nutritional Disorder)

CERCOSPORA LEAF SPOTS (CERCOSPORA SPP)

‘‘‘Cercospora Leaf Spots (Cercospora spp.) ‘‘‘ This disease is characterized by several small, individual lesions that are scattered over the leaves. The lesions may be circular to angular in shape and brown in color with a dark border that may be slightly raised. The centers of the lesions appear to be gray or white.

CLADOSPORIUM BLIGHT (CLADOSPORIUM PISICOLUM)

‘‘‘Cladosporium Blight (Cladosporium pisicolum) ‘‘‘ This disease is characterized by elongated black or brown lesions located on the stems, petioles, peduncles, or pedicels. The lesions found on the leaves develop brown or tan spots that expand through the thickness of the leaf. As infected seedlings emerge, the unfolding leaves exhibit and inward curling. The best form of control is to use clean seed and to grow the peas in dry areas, rather than damp, humid environments. Also, rotating pea crops with another crop for at least two years if peas develop scab will significantly decrease blight possibilities. (Leaf Diseases Caused By Fungi)

DISEASES CAUSED BY NEMATODES

‘‘‘Diseases Caused By Nematodes: ‘‘‘ Plants that are infected with nematodes appear to lose vigor throughout the plant, show excessive branching, generally lack secondary roots, roots quit growing, and galls and lesions begin forming. Proper crop rotation is the only practical method of nematode control.

DOWNY MILDEW (PERONOSPORA SPP)

‘‘‘Downy Mildew (Peronospora spp.) ‘‘‘ This disease is characterized by stunted and distorted plants with fungus growing on all the plant surfaces. These plants may turn yellow while producing more fungus for secondary infections. The plant will develop lesions that are greenish, yellow to brown in color on the upper leaf surfaces and mouse-gray, fluffy areas on the undersides of the leaves directly under the upper lesions. The best forms of control is to use resistant cultivars and fungicides. (Leaf Diseases Caused By Fungi)

FREEZING INJURY

‘‘‘Freezing Injury: ‘‘‘ Plants that have suffered from frost will die at the growing point. Frozen leaves may develop roughened, jagged edges or water soaked, transparent lesions. No effective control methods have been developed. (Environmental Stress)

FUSARIUM ROOT ROT (FUSARIUM SOLANI)

‘‘‘Fusarium Root Rot (Fusarium solani) ‘‘‘ This disease is characterized by reddish brown streaks that appear on the primary and secondary roots especially near the ground line where the seeds have been planted. As the disease matures, these streaks group together. The aboveground symptoms of severely infected plants include graying, yellowing, and dead tissue on the lower foliage and stunted plant growth. There are no resistant cultivars available and so the best form of control is the practice good tillage to reduce soil compaction and use high quality seed. (Root Diseases Caused By Fungi)

FUSARIUM WILTS (FUSARIUM OXYSPORUM)

‘‘‘Fusarium Wilts (Fusarium oxysporum) ‘‘‘ This disease is characterized by a thickened basal internode and the leaves and stems may be brittle and more rigid than those of uninfected plants. Fusarium wilt can be detected fairly early by downward curling of the leaves and stipules. The root system appears normal, however, it is shutting down, but there are no visible indications that it is suffering. The only practical control of the disease is to plant resistant cultivars. (Root Diseases Caused By Fungi)

GRAY MOLD (BOTRYTIS CINEREA)

‘‘‘Gray Mold (Botrytis cinerea) ‘‘‘ This disease is first characterized by fuzzy, gray lesions that streak or surround random, elongated areas of the stem. This usually affects the entire area where the lower leaves are growing. The tip of the pod is usually the area where the infection can be easily spotted. The fungus grows into the young pod and forms a small, oval, tan, water-soaked lesion that spreads throughout the pod. Fungicides are the best form of control. (Leaf Diseases Caused By Fungi)

IRON DEFICIENCY

‘‘‘Iron Deficiency: ‘‘‘ Plants suffering from iron deficiency exhibit a noticeable yellowing in the upper part of the plant. The first part of the plant to become affected is the terminal growth. There is no complete form of control, however, the best form of control at this time is to apply foliar applications of chelate. (Nutritional Disorder)

MAGNESIUM DEFICIENCY

‘‘‘Magnesium Deficiency: ‘‘‘ Plants suffering from magnesium deficiency will experience yellowing between the veins and leaf margins of older leaves. There is no control measures available at this time. (Nutritional Disorder)

MANGANESE DEFICIENCY

‘‘‘Manganese Deficiency: ‘‘‘ Plants suffering from manganese deficiency will experience stunted growth, yellowing of the plant from the top down, reduced pod set and poor pod fill. There are several methods of control which include applying heavy amounts of manganese to the soil, drilling manganese sulfate at the times of seeding if the problem is known beforehand, and applying foliar applications of manganese chelate at the first bloom on plants that have already been developing. (Nutritional Disorder)

NITROGEN DEFICIENCY

‘‘‘Nitrogen Deficiency: ‘‘‘ Plants suffering from nitrogen deficiency appear short and spindly with very small yellow leaves and stipules. The plant rarely produces blossoms and as the plant becomes older, leaves begin to defoliate from the lower part of the plant moving upwards. The best form of control is to apply a starter fertilizer which will include the proper amount of nitrogen. (Nutritional Disorder)

PEA ENATION MOSAIC (PEMV)

‘‘‘Pea Enation (PEMV) ‘‘‘ This disease is characterized by plant distortion as the plant is still young. As the plant grows and matures, it may take on symptoms of stunted plant growth, yellow flecks, leaf and pod distortion and reduced seed size and quality. The best form of control is the use of resistant cultivars. (Diseases Caused By Viruses)

PEA SEEDBORNE MOSAIC (PSbMV)

‘‘‘Pea Seedborne Mosaic (PSbMV) ‘‘‘ This disease is characterized by stunted and malformed plants that may also never reach maturity. The best form of control is to use resistant cultivars. (Diseases Caused By Viruses)

PEA STREAK (PSV)

‘‘‘Pea Streak (PSV) ‘‘‘ This disease kills young plants very early and very quickly. If the plant is older when it becomes infected, it may develop a variety of brown or purple leaf and stem lesions or streaks. The best forms of control include planting resistant cultivars and eliminating aphid populations. (Diseases Caused By Viruses)

PEA STUNT (RCVMV)

‘‘‘Pea Stunt (RCVMV) ‘‘‘ This disease kills young plants very early before they get a chance to bloom. As the plants becomes older, the infections will cause stunted growth and terminal rotting. The best method of control is to use resistant cultivars. (Diseases Caused By Viruses)

PHOSPHORUS DEFICIENCY

‘‘‘Phosphorus Deficiency: ‘‘‘ Plants suffering from phosphorus deficiency have symptoms similar to those of plants with nitrogen deficiency which include dark, bluish green foliage. The plants wither prematurely and have a dull appearance. The best form of control is to apply a starter fertilizer which will contain the proper amounts of phosphorus. (Nutritional Disorder)

POTASSIUM DEFICIENCY

‘‘‘Potassium Deficiency: ‘‘‘ Plants that are suffering from potassium deficiency are severely stunted with shortened internodes and yellow leaves. The leaves may curl upward and inward. The best form of control is to apply a potassium fertilizer. (Nutritional Disorder)

POWDERY MILDEW (ERYSIPHE PISI)

‘‘‘Powdery Mildew (Erysiphe pisi) ‘‘‘ This disease is characterized by small lesions that appear on the upper surface of the lowest and older leaves. These lesions are scattered on the leaves and as they mature and develop they look like white, powdery areas. Severely infected areas may even look blue-white. Fortunately, there are resistant cultivars available and should be used since they offer the best form on control. However, other control measures can be used which include chemical control with benomyl or sulfur, but must be properly timed to be effective. Also, planting early and using sprinkler irrigation will minimize the chances of having a crop infected with powdery mildew. (Leaf Diseases Caused By Fungi)

PYTHIUM DISEASES (PYTHIUM SPP)

‘‘‘Diseases Caused by Pythium spp. (Pythium spp.) ‘‘‘ This disease is characterize by soft, rotted seeds and fungus infested soil surrounding the seed. The best form of control is to use resistant cultivars and apply seeds with protective fungicides. (Seed and Seedling Disease)

PYTHIUM ROOT ROT (PYTHIUM SPP)

‘‘‘Pythium Root Rot (Pythium spp.) ‘‘‘ This disease is characterized by young, small inefficient roots. The infected roots are tan to light brown. The plant usually experiences stunted growth and is yellow because of the poorly developed root system. The best form of control is to use resistant cultivars. (Root Diseases Caused By Fungi)

PYTHIUM TIP BLIGHT (PYTHIUM SPP)

‘‘‘Pythium Tip Blight (Pythium spp.) ‘‘‘ This disease is characterized by water-soaked areas on the tips of young plants. These areas quickly lose their green color and fall off the plant. The dry, dead tissue takes on a straw or black color depending on the environmental conditions. This disease is usually only seen during long periods of high humidity and cloud cover, interspersed with heavy rains. (Leaf Diseases Caused By Fungi)

RHIZOCTONIA SOLANI SEEDLING ROT (RHIZOCTONIA SOLANI)

‘‘‘Rhizoctonia Solani Seedling Rot (Rhizoctonia solani) ‘‘‘ This disease is characterized by lesions that appear to be water-soaked as the seedling emerges. These lesions will develop a reddish brown to brown color and often the growing point may be affected causing it to die. Mature plants that become infected will also develop the reddish brown, sunken lesions that may girdle the plant and cause severe stunting. The best form of control is to apply fungicidal seed treatment chemicals in connection with insecticide applications of captan. (Seed and Seedling Disease)

SCLEROTINIA ROT (SCLEROTINIA SCLEROTIORUM)

‘‘‘Sclerotinia Rot (Sclerotinia sclerotiorum) ‘‘‘ This disease is characterized by watery lesions that develop at later stages of growth and can appear on any plant structures if the plant is not exposed to good air circulation. As the disease matures, fluffy, white dense mats of mycelium develop causing affected areas to become slimy. Fungicides provide a good measure of control and should be used in connection with a five-year crop rotation avoiding land previously used for peas and beans. (Leaf Diseases Caused By Fungi)

SEPTORIA BLOTCH (SEPTORIA PISI)

‘‘‘Septoria Blotch (Septoria pisi) ‘‘‘ This disease is characterized by yellow and straw colored areas on a plant that are inconsistent in size and shape. The disease is usually found on the lower parts of the plant. The best form of control is to practice good crop rotation. (Leaf Diseases Caused By Fungi)

THIELAVIOPSIS ROOT ROT (THIELAVIOPSIS BASICOLA)

‘‘‘Thielaviopsis Root Rot (Thielaviopsis basicola) ‘‘‘ This disease is characterized by small, irregular black lesions on the lower leaves of a plant and a dry, dead taproot and lateral roots. The only measure of control is to avoid field that have been infested with the disease. (Root Diseases Caused By Fungi)

WATER CONGESTION

‘‘‘Water Congestion: ‘‘‘ Plants that have been water congested have very small water soaked spots near the outer edge and on the underside of foliage. No control methods have been developed. (Environmental Stress)