Mullett Martin, Peace Andy, Brown Anna
Forest Research, Alice Holt Lodge, Farnham, Surrey, GU10 4LH, UK.
Forest Research, Northern Research Station, Roslin, Midlothian, EH25 9SY, UK.
Plant Dis. 2016 Jul;100(7):1271-1277. doi: 10.1094/PDIS-11-15-1306-RE. Epub 2016 Apr 8.
Dothistroma septosporum is a serious foliar pathogen of pines in Britain. To determine the contribution of spores produced on abscised needles to the D. septosporum inoculum load in a forest environment, survival of the fungus was investigated in commercially grown plantations of Corsican pine (Pinus nigra subsp. laricio) in southern England. The fungus persisted for longer in abscised needles retained in the canopy compared with needles on the litter layer of the forest floor. High relative humidity had a significant negative effect on persistence in the canopy needles, highlighting the effect of moisture on rates of microbial decay. The median lethal time 50 (LT) of infective propagules from needles in the litter layer was 20 to 28 days, whereas for needles suspended in the canopy it was 34 to 48 days. Microsatellite markers revealed that the population of D. septosporum deemed persistent (i.e., recovered from abscised needles after exposure for 28 to 32 weeks) was similar to the general population of D. septosporum in the forest stand (i.e., isolates recovered from attached needles and after exposure for only 4 weeks). Overall, abscised needles with acervuli of D. septosporum contribute only moderately and for a limited time to inoculum levels of the pathogen in an infected forest stand.
七针散斑壳菌是英国松树的一种严重叶部病原菌。为了确定脱落针叶上产生的孢子对森林环境中七针散斑壳菌接种量的贡献，在英格兰南部商业种植的科西嘉松（黑松亚种拉里西松）人工林中研究了该真菌的存活情况。与落在森林地面凋落物层的针叶相比，留在树冠层的脱落针叶上的真菌存活时间更长。高相对湿度对树冠层针叶上真菌的存活有显著负面影响，突出了水分对微生物腐烂速率的影响。落在凋落物层的针叶上感染性繁殖体的半数致死时间50（LT）为20至28天，而悬于树冠层的针叶上则为34至48天。微卫星标记显示，被认为具有持久性的七针散斑壳菌群体（即暴露28至32周后从脱落针叶中分离得到的菌株）与林分中七针散斑壳菌的总体群体相似（即从附着针叶中分离得到的菌株以及仅暴露4周后分离得到的菌株）。总体而言，带有七针散斑壳菌分生孢子盘的脱落针叶对受感染林分中该病原菌接种水平的贡献仅为中等程度且持续时间有限。
