ABSTRACT
Deer, particularly white-tailed deer (Odocoileus virginianus), damage row
crops such as soybean (Glycine max L.) and are a perceived problem in the continental US. Currently, the only
widely used technique to control deer from crop browsing is establishment of
fences, which is expensive, labor intensive, and most of the time ineffective.
Studies have shown that sicklepod, Senna
obtusifolia (L.),
contains anthraquinone derivatives, which in separate studies were shown to be
toxic to cattle, rats, rabbits, and horses, and repel herbivores primarily
birds. However, information of the deer-repelling property of anthraquinone in sicklepod is lacking. Field tests conducted at
our Captive Deer Facility at MississippiStateUniversity(MSU) confirmed the deer-repelling property of anthraquinone extracts from
sicklepod. Soybean plants applied with control treatment (water) were browsed
by deer, while plants applied with sicklepod anthraquinone extracts were
avoided. Using chromatography techniques, we found the levels of anthraquinone
derivatives (chrysophanol, emodin) in sicklepod plant parts in the order: root
> fruit > stem/leaf. Hydrolysis of water extracts of sicklepod seed
produced high emodin concentration, suggesting emodin glycoside as the main
form of anthraquinone glycoside in sicklepod seed. Deer-repelling compounds can
be extracted in its pure form from sicklepod and applied on soybean to increase
its repelling efficacy on deer, and at the same time protect soybean yields.