Pratylenchus spp.
P. neglectus
P. thornei
P. penetrans
P. brachyurus
P. crenatus
P. scribneri
P. zeae
P. hexincisus
P. fallax
- Symptoms: Above ground symptoms of root lesion nematodes are often indistinct and difficult to identify, but include poor vigor, stunted growth, cereals tillering poorly, as well as wilting in response to moisture stress (picture at left). Often, crop growth in an infected field will be irregular or patchy. Below ground, cereal roots will display generalized root browning, with lesions rapidly coalescing to produce extensive areas of discoloration. Lesions are only readily observed on the roots in the very early stages of infection. Lateral roots will be reduced in both length and number, and the root system may be thin and poorly branched or appear necrotic (picture at right).
- Development: Root lesion nematodes, which are migratory endoparasites, may reproduce and then re-infest the roots several times per cropping season. Adult and juvenile root lesion nematodes have the ability to move within and between roots and soil, and often will, after a root has been damaged, migrate in favor of a fresh site. An actively feeding female can lay one egg per day, which will hatch after ten days, and reach adulthood in approximately thirty-five days. In drought conditions, where soil is dry and no living roots are available, root lesion nematodes become anhydrobiotic, and rehydration and return to activity can take as little as a few hours.
- Hosts/Distribution: Root lesion nematodes have world-wide distribution, with a wide host range that includes field, horticultural, and ornamental crops, both annual and perennial. Grass and broad-leaf weeds also play host to root lesion nematodes.
- Importance: Root lesion nematodes are distributed world-wide, and cause yield losses on wheat as high as 70%. Damage is greater in conditions of moisture stress and often occurs on lighter soil types with poor water holding capacity.
References:
- Dr. Vivien Vanstone- Senior Plant Nematologist, Dept. Agriculture and Food Western Australia, South Perth, Western Australia.
- Dr. Sharyn P. Taylor- Senior Advisor, Plant Health Australia, Canberra. Formerly Senior Nematologist, SARDI, South Australia, Australia.