The Cucurbitaceae is a genetically diverse group of plants containing several important commodity crops in many parts of the world such as cucumber, pumpkin and melon. In the last decades, fruit rot caused by Stagonosporopsis spp. became a major disease in both field grown and greenhouse grown cucurbits. Yield losses due to Stagonosporopsis can show seasonal peaks up to 30%. Despite its economic importance, only limited information is available about growth characteristics of Stagonosporopsis cucurbitacearum. Our in vitro studies with different media indicated an optimal growth rate of the fungus within the range of pH 5 to pH 6. Independent of the carbon source (sucrose, glucose, dextrose, fructose) alkalization of 1–3, 5 pH units was noticed under both carbon deprivation and excess. The observed pH modulation could not always be related with a more favourable growth environment. The key factor influencing both pH modulating capacity and growth showed to be the nitrogen source. Supplying nitrate, ammonium or a combination of both, the environmental pH respectively increased, decreased or remained stable. In addition to a pH-elevating effect, nitrate supply also stimulated growth whilst growth on ammonium containing media was seriously affected. This research highlights the importance of the nitrogen source in the growth and regulation of environmental pH by fungi and adds in our understanding of S. cucurbitacearum pathogenicity.

在葫芦科是包含在世界的许多地方，如黄瓜，南瓜和甜瓜几个重要的商品作物植物的遗传多样性组。在过去的几十年中，由腐霉菌引起的果实腐烂。在田间栽培和温室栽培的葫芦科植物中均成为主要疾病。链球菌引起的产量损失可能会出现季节性高峰，最高可达30％。尽管具有经济重要性，但关于葫芦科南瓜的生长特性的信息很少。我们在不同培养基上的体外研究表明，在pH 5至pH 6范围内，真菌的最佳生长速率。与碳源（蔗糖，葡萄糖，右旋糖，果糖）无关，碱化为1-3，可观察到5个pH单位在碳缺乏和过量的情况下。观察到的pH调节不一定总是与更有利的生长环境有关。影响pH调节能力和生长的关键因素是氮源。提供硝酸盐，铵或两者的组合，环境pH分别升高，降低或保持稳定。除了提高pH值，硝酸盐供应还刺激了生长，同时严重影响了含铵介质的生长。南瓜葡萄球菌的致病性。