Problems in tree replacement. 1. The root-lesion nematode Pratylenchus coffeae Zimmerman as a factor in the growth of replant trees in apple orchards.

Abstract

The root-lesion nematode Pratylenchus coffeae Zimmerman is widely distributed in apple orchards in the Stanthorpe district. It is restricted to the non-suberized fibrous roots which are destroyed as a consequence of heavy infestations. Apple seedlings grown in soil infested with P. coffeae were stunted when compared with seedlings grown in the same soil after pretreatment with "D-D" or formalin. The parasite appears to be the most important factor causing the unthrifty growth of replant trees in many old orchards. No apple rootstocks available in the district are immune to the parasite. Fumigation of heavily infested soil before replanting offers a partial solution to the problem.