Publication 360, Guide to Fruit Production: Nematodes

Pub 360, Guide to Fruit Production > Chapter 9, Other Pests and Disorders > Nematodes

Excerpt from Publication 360, Guide to Fruit Production, 2012-13
Order this publication

1. Introduction & Symptoms
2. Thresholds
• Table 9-1. Thresholds for Nematodes on Fruit Crops
3. Nematode control
   • Table 9-2. Control of Nematodes and and Other Soil-borne Pests before Planting Fruit Crops
4. Other topics in Other Pests and Disorders
   • Deer Control
   • Mouse and Vole Control in Orchards
   • Controlling Rabbits
   • Bird Control
   • Control of Southwest Injury on Fruit Trees
   • Preventing Heat Stress and Fruit Sunburn on Apple and Pear Trees
5. Chapter 9 - Other Pests and Disorders - (PDF 113 kb)
6. Related Links

Introduction & Symptoms

Plant parasitic nematodes can cause significant yield losses to many horticultural crops. The extent of loss depends on the crop, nematode species and soil populations.

The most destructive and common nematodes in Ontario fruit crops are root-lesion (Pratylenchus penetrans) and northern root-knot (Meloidogyne hapla). The northern root-knot nematode is becoming more prevalent. The pin (Paratylenchus sp.) and dagger (Xiphinema sp.) nematodes occasionally cause yield losses to some fruit crops in isolated fields. The dagger nematode is mainly a virus vector on grape, raspberry and apple.

Symptoms of nematode injury include:

• uneven plant growth
• poor plant establishment
• weakened plants over time
• poor root growth
• knots or galls on roots
• excessive branching of roots, hairy root symptoms

On strawberries:

• Root-lesion nematodes cause discolouration of the fine feeder roots and tiny, brown, scratch-like lesions on the young white roots. These lesions merge to form large brown areas. Root-lesion nematodes are involved in black root rot and aggravate verticillium wilt of strawberries and other host plants. Severely infected plants appear stunted and unthrifty.
• Root-knot nematode feeding stimulates root cells to enlarge. Enlarged cells look like small galls or beads (1 mm). As more and more nematodes establish feeding sites, they join together to become one larger root-knot.

On raspberries:

• Root-lesion nematode feeding causes scratch-like lesions on roots, similar to the symptoms on strawberry roots. Severely infested plants have thinner and fewer canes per crown. Up to 25% of first year canes may be killed by severe infestations of these nematodes.
• Dagger nematodes spread tomato ringspot virus, which causes crumbly berries, mottled leaves and cane dieback.

On tree fruits:

• Root-lesion nematodes can be a major cause of orchard replant failures. They can cause a decline in vigour of existing peach and cherry orchards. These nematodes cause small brown lesions on the white lateral roots and kill the fine feeder roots. When lesions merge, the entire root system appears discoloured. Root lesions are frequently invaded by other pathogens which can cause root rot. Severely affected trees may lose all feeder roots; young replant trees may die. Existing trees lack uniformity.

For more information, see OMAFRA Factsheet, Sampling Soil and Roots for Plant Parasitic Nematodes, Order No. 06-099.

Information on how to sample soil for nematodes and where to send the samples is found in Appendix D. Diagnostic Services.