Colonization of vines by Petri disease fungi, susceptibility of rootstocks to Phaeomoniella chlamydospora and their disinfection

ABSTRACT: Petri disease is complex, attacks young vine plants and it is difficult to be controlled. The fungus Phaeomoniella chlamydospora (Phc) has been identified as the main causative agent of this disease. This study aimed to evaluate the prevalent colonization of the Petri disease fungi in different portions of vine plants; to assess the susceptibility of grapevine rootstocks to the fungus P. chlamydospora; to assess the effect of solarization and biofumigation, followed by hot-water treatment (HWT), on the disinfection of cuttings of the rootstock IAC 766 infected with P. chlamydospora, and assess the effect of solarization and biofumigation, followed by HWT, on the rooting of cuttings of the rootstock IAC 766. For the prevalent colonization test, the fungus species detected and identified in ‘Niagara Rosada’ grafted on two rootstocks different were Phc and Phialemoniopsis ocularis. This is the first report of P. ocularis in a young vineyard in Brazil. Both fungi, in particular Phc, colonized only the plant’s basal part, drawing attention to the rootstock as target for control measures. Measurement of the dark streaks in the vascular system revealed that Golia was the least susceptible rootstock, and IAC 572 was the most susceptible to Phc. Moreover, biofumigation or temperature of 37°C applied for 7 and 14 days, both followed by HWT, suppressed Phc in cuttings of the rootstock IAC 766 without hampering their rooting. Meanwhile, new studies are needed to validate the efficiency of these disinfection techniques.

摘要：皮特里病（Petri disease）是一类复杂的葡萄病害，可侵染幼龄葡萄植株且防治难度极高。研究已确认厚膜披毛壳菌（Phaeomoniella chlamydospora，简称Phc）为引发该病害的主要致病菌。本研究旨在完成四项研究目标：一是调查皮特里病相关真菌在葡萄植株不同组织部位的定殖分布特征；二是评估不同葡萄砧木对Phc的感病性；三是探究太阳能消毒、生物熏蒸结合热水处理（hot-water treatment，HWT）对感染Phc的IAC 766号砧木插穗的消毒效果；四是评估该联合处理方案对IAC 766号砧木插穗生根的影响。在定殖分布调查中，研究人员在嫁接于两种不同砧木的‘尼亚加拉玫瑰莎’（Niagara Rosada）葡萄植株中，检测并鉴定出Phc与眼状瓶霉（Phialemoniopsis ocularis）。这是巴西境内首次在幼龄葡萄园中报道眼状瓶霉的侵染发生。两种真菌（尤以Phc为著）仅定殖于植株基部部位，提示砧木可作为病害防控的核心靶标。对植株维管束暗色条纹的量化检测结果显示，Golia砧木对Phc的感病性最低，而IAC 572砧木的感病性最高。此外，采用生物熏蒸，或37℃条件下分别处理7天、14天的太阳能消毒，后续结合热水处理，均可在不抑制IAC 766号砧木插穗生根的前提下，有效灭活插穗内携带的Phc。不过，仍需开展进一步研究以验证该类消毒技术的实际应用效能。