柔枝莠竹[Microstegium vimineum（Trin.）A. Camus）属于禾本科一年生C4植物，原产亚洲，分布极为广泛，广泛入侵美国东南部地区林地，抑制树木的生长和森林更新，改变土壤性质及结构。对它的防治现在主要集中在物理、人工、生物和化学等方法，但效果十分有限。利用生物防治的方法控制外来入侵杂草已经有成功案例。全球已经从柔枝莠竹上分离得到9科23种致病真菌，但是迄今，还没有发展出行之有效的生物防除技术，遏制其入侵的势头。所以，十分有必要开展柔枝莠竹种群自然病害的调查和病原物的分离鉴定，筛选出致病性较强的致病真菌并对其潜力进行评估，为生物防治提供有潜力的候选菌株。 从2014~2017年对中国的分布区的柔枝莠竹叶斑病、叶枯病病害进行了系统调查，共采集到634份病叶样本，获取得445株分离物，接种到离体柔枝莠竹叶片上测试致病力，获得81株致病真菌，结合分生孢子及孢子梗形态及DNA序列分析，分类包括平脐蠕孢、突脐蠕孢、弯孢、黑孢、茎点霉、盘多毛孢、链格孢、棒孢、内脐蠕孢属到8个属17种致病真菌。其中，13种69株是首次在柔枝莠竹上报道。通过离体、活体致病性测试以及田间网室小区试验筛选出稷平脐蠕孢菌株SX 5-2作为柔枝莠竹生防潜力真菌。该菌在实验室条件下105个孢子/ml的孢子悬浮液对柔枝莠竹达到90%以上的防除效果，田间达到80 %以上的防除效果。 寄主范围测试结果表明：稷平脐蠕孢菌SX-5-2对水稻、小麦、高粱、大豆、棉花、蔬菜以及高羊茅、结缕草草坪安全，仅对玉米敏感性高，因此，有潜力用于控制上述田间禾本科杂草。试验结果表明菌株能够防除狗尾草、马唐、看麦娘、菵草、牛筋草、柳枝稷、稗草、油芒、芒、金茅、日本莠竹、莠竹、荩草、苏丹草、千金子、早熟禾、狗牙根等17种目标杂草，并对马唐、日本莠竹、莠竹、苏丹草、柳枝稷、千金子、稗草7种杂草的防治效果达到75 %以上。 该菌的生物学特性测试表明：MV-PDA培养基对真菌生长和产孢最好，30 ℃和28 ℃为该菌营养生长和产孢的最适温度；适宜pH范围为4 ~ 8；该菌的最佳氮源为蛋白胨，最佳碳源物质为麦芽糖，并在该条件下也能较好的产孢；产孢对光照有特殊的要求，20 W黑光灯（λ= 365 nm）刺激有利于稷平脐蠕孢菌株SX 5-2产孢。而该菌的分生孢子萌发需在高湿度条件(> 80%)以及适当的高温(28~32 ℃)，萌发率最高的是以柔枝莠竹汁液为营养的悬浮液；除紫外灯的三种光照条件对稷平脐蠕孢菌株孢子萌发没有显著影响，其分生孢子的致死温度为55 ℃。 为探究稷平脐蠕孢菌株SX 5-2工业化生产的潜力，还探究了不同基质、配比等条件对SX 5-2菌株产孢的影响，得出如下结论：麦麸和锯屑是SX 5-2产孢的适宜培养基；以麦麸和圆杉木屑5 ：5等比例混合中加入1.25倍水的每克干物质的产孢量为最大；其最适产孢温度为28 ℃。随着照光时间的延长，产孢量逐渐增大，培养温度为30 ℃、照光4天时产孢量1.83×106个/克达到最大。但是，随着照光时间的延长，孢子萌发率先逐渐增大后趋于平稳甚至下降。 从以上结果得出，该菌对柔枝莠竹致病力强，专化程度高，适应性广，安全性高，并且在工业化生产过程中分生孢子容易大量获得，极具发展成为柔枝莠竹除草剂的潜力。但是，产业化还需要深入开展生产工艺、剂型及应用技术的研究。

Microstegium vimineum as a Poaceae annual C4 plant, which is native to Asia, now widely distributed and heavily invaded woodlands in the southeast of United States. It invades forest, reduces tree growth and regeneration, and changes soil properties and structures. The control measurements have been attempted on the physical, artificial, biological and chemical methods, but their effects are very limited. It is reported that some successful cases of using biological control methods to controlling other invasive weeds worldwide. 23 speciese of pathogenic fungi from 9 families have been isolated from M. vimineum in the world, but effective biological control agents have not been found so far. Therefore, it is very necessary to carry out investigation of natural diseases of M. vimineum population and isolation of pathogens, screen for pathogenic fungi with strong pathogenicity, evaluate their potential, and provide potential candidate strains for biological control. From 2014 to 2017, we conducted investigation about the leaf spot and leaf blight on M. vimineum in China. A total of 634 diseased leaf samples were collected and 445 isolates were obtained. The eighty-one pathogenic fungi were isolated from the leaves of the M. vimineum. According to the morphological traits of conidia and DNA marker sequence analysis, they were classified into 8 genera of 17 species of pathogenic fungi including Bipolaris, Exserohilum, Curvularia, Nigrospora, Phoma, Alternaria, Corynespora, Drechsler. Among them, 13 species of 69 strains were reported for the first time in the M. vimineum. Through the pathogenicity test and field experiment, SX 5-2 was screened out as biological agent of M. vimineum. Disease index was up to 90 % at a spore suspension concentration of 105 spores/ml on the Microstegium vimineum under laboratory conditions and more than 80 % in the field trial. According to host range test B. panici-miliacei SX-5-2 was safe for rice, wheat, sorghum, soybean, cotton, vegetables, zoysia japonica turf but susceptiable to maize. Therefore, the strain SX 5-2 had the potential to control gramineous weeds in the non-corn fields. The results of effectiveness evaluation tests showed that the strains could effectively control 17 target weeds: Setaria viridis (L.) Beauv., Digitaria sanguinalis (L.) Scop., Alopecurus aequalis Sobol., Beckmannia syzigachne (Steud.) Fern., Eleusine indica (L.) Gaertn., Panicum virgatum L., Echinochloa crusgalli (L.) Beauv, Eccoilopus cotulifer (Thunb.) A. Camus, Miscanthus sinensis Anderss., Eulalia speciosa (Debeaux) Kuntze, Microstegium japonicum (Miq.) Koidz, Microstegium nodosum (Kom.) Tzvel., Arthraxon hispidus (Thunb.) Makino, Sorghum sudanense (Piper) Stapf, Leptochloa chinensis (L.) Nees, and among them, the control effects on seedlings or aging plants like Digitaria sanguinalis (L.) Scop, Microstegium japonicum (Miq.) Koidz, Microstegium nodosum (Kom.) Tzvel, Sorghum sudanense (Piper) Stapf , Panicum virgatum L., Echinochloa crusgalli (L.) Beauv, and Leptochloa chinensis (L.) Nees reached 75 % or more. The biological characteristics test of B. panici-miliacei SX-5-2, MV-PDA medium was the optimum medium for growth and sporulation. The optimum temperature for vegetative growth and sporulation was 30 ℃ and 28 ℃. The pH range was 4 ~ 8. The optimum nitrogen and carbon source was peptone, maltose, respectively, which was also conducive to sporulation. Black light（λ= 365 nm）stimulation was beneficial to sporalution of the strain SX 5-2. The germination of the strain should be under high humidity (> 80%) and appropriate high temperature (28 ~ 32 ℃). The highest germination rate was obtained at the suspension of Microstegium vimineum extract. It was not found that illumination influenced on the spore germination rate of the strain SX 5-2 Bipolaris panici-mileacei except UV lamp. It is the lethal temperature of conidia in 55 ℃. In order to explore mass-production of the strain SX 5-2, the effects of different substrates, ratios, and other conditions were studied on the sporulation ability of SX 5-2 strain, and reached the following conclusions: wheat bran mixed with fir sawdust culture medium was suitable for SX 5-2; The spore production per gram of dry matter was significant higher than other combinations when 1.25 times sterile water was added to the mixture of wheat bran sawdust at a ratio of 5 : 5.. The optimum sporulation temperature was 28 ℃. With the prolongation of illumination time, the sporulation of each culture temperature gradually increased. The sporulation level reached the maximum at 1.83 × 106 / gram for four days’ illumination at the culture temperature of 30 ℃. However, spore germination rate increased gradually firstly and tended to steady or even decreased with continuing illumination. The above results indicated that B. panici-miliacei SX 5-2 strain had strong pathogenicity, specialization on M. vimineum, safe to most of the main crops, easy to mass-production. It may be developed into a potential biological control agent against M. vimineum. However, the commercialization of this strain needs to focus on the research of mass-production processes, fomulation and application techniques.