Nematode Pests of Horticultural Crops and their Management (1+1)

Peach

(II) PEACH
The important nematodes of peach include Meloidogyne spp., Paratylenchus spp., Pratylenchus spp., Criconemella spp. and Xiphinema spp.

a. Root-knot nematode (Meloidogyne spp.):

• At least five species of root-knot nematode have been reported to damage peaches in one or the other peach growing areas of the globe.
• In India, while M. hapla is restricted to colder regions of Himachal Pradesh, M. incognita and M. javanica are prevalent in warmer peach growing areas of Delhi, Punjab and Haryana.
• Nematode is a sedentary root endoparasite. Juveniles (J2_s) prefer root tips for penetration which are devitalized and root elongation ceases.
• Secondary and tertiary branches are produced with variable size of galls, giving roots the brush-like appearance.
• Uneven size of trees in the orchard, smaller ones showing poorly developed foliage, poor vigour, dieback of twigs give an indication of root-knot infestation.

b. Pin nematode (Paratylenchus spp.):

• These are the smallest representatives among the plant parasitic forms which attack herbaceous as well as woody plants.
• At least seven out of total of more than 100 species are associated with peach. Of these, P. prunii, P. nannianus and P. curvitatus are more common.
• The nematode produces non-specific symptoms like stunting of the plant, yellowing of foliage and under-sized fruits.
• The extent of damage depends upon the age and vigour of the plant at the time of infestation.

c. Lesion nematode (Pratylenchus spp.):

• Most of the eight species of root lesion nematodes reported from peach are from different parts of USA. Of these P. penetrans, P. pratensis and P. vulnus are more prevalent and damaging.
• Pratylenchus coffeae has been reported from peach in India.
• Root lesion nematode is a migratory endoparasite, juveniles and adults of which move inter and intra-cellularly in the cortical tissue causing extensive, dark lesions on the roots.
• Feeder roots are deteriorated fast.
• Above-ground symptoms appear in form of general nutritional deficiency symptoms like weak plants with reduced vigour that bear less number of under-sized fruits.
• Nematode poses replant problem in peach.

d. Criconemella xenoplax.:

• Criconemella. xenoplax is the only creconematide reported from peaches in India.
  
• It is a sedentary ectoparasite that causes pits on the roots and destroys the feeder roots.
• As a result stunting, chlorosis, leaf drop and loss of vigour of peach trees occur.

Management:

• Nursery should be raised in nematode free soil.
• Only healthy, nematode free planting stock should be transplanted in the field.
• Pre-plant soil fumigation, weed removal, nutritional supply in form of organic amendments and use of resistant root stocks help in keeping the nematode population under control.
• Root dip treatment in oxamyl @ 0.024g/litre kills the nematode population.