A pilot study to determine the extent of possible biocontrol resistance in St. John's wort, the effect of St.John's wort on forage availability and alternative tools for control.

贯叶连翘是一种原产于欧洲的多年生植物，可以**繁殖和传播，特别是在受干扰的地点和牧场。圣约翰麦芽汁是1947年不列颠哥伦比亚省的第一份文件，是一个很好的竞争对手；它减少了当地的植物物种，并在**过程中会伤害牲畜。圣约翰草的叶子中含有化学物质金丝桃素和金丝桃素。摄入金丝桃素**会导致水泡、繁殖性能下降，在极少数情况下，还会导致牲畜死亡。据报道，金丝桃素是应对食草性疾病的一种防御性化合物。生防甲虫金丝桃历来是圣约翰草的有效生防剂。在不列颠哥伦比亚省南部，甲虫的处理使圣约翰麦芽汁的数量减少到不到治疗前的2%。不幸的是，观察表明，圣约翰的麦芽汁正在重新出现在这片土地上，而生防甲虫的表现并不像历史上那样好。众所周知，食草动物等应激源会触发植物中的形态和化学捕食者防御机制，如毒素的产生。圣约翰草可能具有过量产生金丝桃素和金丝桃素的能力，作为一种对甲虫食草性反应的捕食防御机制。**为了解决圣约翰草在公元前复活的问题，需要新的方法来控制圣约翰草。陶氏化学的除草剂在控制圣约翰草方面历来是有效的。如果圣约翰草的种群对生防甲虫产生了抗药性，可能**就需要使用这种除草剂。我们将**确定BC的3个地点是否存在生防抗性以及抗性程度。我们将与**Corteva Agiscience合作：1)确定圣约翰草种群中是否存在生防抗性；2)**测试不同Corteva Agriscience除草剂对圣约翰草种群的效果；以及3)我们将**提供简单的田间技术，以确定潜在的抗性植物和替代杂草控制方案**圣约翰麦芽汁的控制方案。

St. John's wort (Hypericum perforatum) is a perennial plant native to Europe that can reproduce and spread**aggressively, particularly in disturbed sites and rangelands. St. John's wort was first document in British**Columbia in 1947 and is an excellent competitor; it diminishes native plant species and can harm livestock in**the process. St. John's wort contains the chemicals hypericin and hyperforin in its leaves. Ingestion of hypericin**results in blisters, reduced reproductive performance, and in rare cases, death in livestock. Hyperforin has been**reported to serve as a defensive compound in response to herbivory.**The biocontrol beetle, Chrysolina hyperici, has historically been an effective biocontrol of St. John's wort. In**southern BC treatment by the beetle as reduced St. John's wort populations to less than 2% of pretreatment**levels. Unfortunately, observations indicate that St. John's wort is resurging on the landscape and the biocontrol**beetles are not performing as well as they have historically. Stressors, such as herbivory, are known to trigger**morphological and chemical predator defense mechanisms in plants, such as the production of toxins. St.**John's wort may have the ability to overproduce toxins hypericin and hyperforin as a predatory defense**mechanism in response to beetle herbivory.**To tackle the issue of resurging St. John's wort in BC, new methods are needed to control St. John's wort. Dow**has herbicides that have historically been effective at controlling St. John's wort. The use of this herbicide may**be needed if the population of St. John's wort has developed resistance to the biocontrol beetle. We will**determine if biocontrol resistance exists and the extent of resistance at 3 sites in BC. We will collaborate with**Corteva Agriscience to: 1) determine if biocontrol resistance is present within St. John's wort populations 2)**test the efficacy of different Corteva Agriscience herbicides on St John's wort populations; and 3) we will**present simple field based techniques for identifying potentially resistant plants and alternative weed control**options for St.John's wort control.