What percentage of endophytic stems in turf can eliminate feeding from many surface insects?

The ability of endophytic stems in turf to deter feeding from various surface insects is significantly influenced by the presence of specific endophytes. Research indicates that having around 40% endophytic stems in a turfgrass system can substantially reduce the feeding activities of many surface-dwelling insects. This is primarily due to the production of alkaloids and other secondary metabolites by the endophytes, which act as natural repellents or deterrents to pests.

The percentage indicates a threshold where the benefits of endophyte activity become pronounced, making it effective in managing insect populations and improving the health of the turf. A level of 40% creates an environment where the protective effects of the endophytes can be maximized, thereby helping turfgrasses withstand pest pressures more effectively. This is why the answer highlighting 40% is considered the correct response.