Survival of Fusarium circinatum in soil and Pinus radiata needle and branch segments

Survival of Fusarium circinatum in colonized pine needles and wood pieces was measured. Naturally colonized branches and their needles were cut into small pieces and placed in mesh bags on the soil surface at two locations in Northern Spain. Pieces were recovered periodically, cultured on a selective medium and microscopically examined to identify the species. After 507 days, F. circinatum was recovered from 0 to 27% of the wood pieces and from none of the needles. After 858 days, F. circinatum was not recovered from any wood pieces but was found to be present on 1 out of 220 needle pieces analyzed. Artificially infested pieces of wood and needles were placed on 5-mm sieved soil either in plastic boxes at controlled temperature or in mesh bags under field conditions. No survival was recorded after 794 days under field conditions and the decline over time occurred more rapidly in inoculated pieces under field conditions. Soil was also infested with conidia of F. circinatum and survival was estimated. No conidia were recovered after 224 days at 30oC, although at 20oC and at 5oC the respective populations were 20 and 3700 cfu/ g soil. F. circinatum was not recovered from 2-mm-sieved soil collected under pitch canker-infected pines. Results indicate that branch segments and needles naturally colonized by F. circinatum will not be a potential source of inoculum, and the fungus in soil is not likely to contribute to reinfection of new plantations after two years. This article is protected by copyright. All rights reserved.