In meetings with organic rice producers there is a common theme – we need to increase organic nitrogen fertility and control weeds in rice! The two most often mentioned weeds in rice (outside weedy or red rice) is Hemp Sesbania and Northern Jointvetch.
These weeds are very similar in appearance, at least as very young plants and both are problems throughout the semi-tropical areas of Texas to Mississippi. Hemp sesbania can grow to be so bad that you can’t get the combine through, and those portions of the field are just abandoned.
In doing a little research I found that the fungus Colletotrichum gloeosporioides f. sp. Aeschynomene packaged and labeled as LockDown Bioherbicide, is very effective on Northern Jointvetch and has been effectively used in Arkansas rice fields for many years. Now Arkansas rice farmers don’t have a real problem with Hemp Sesbania but in researching the fungus I have found several research reports that show this fungus can also be very effective against Hemp Sesbania (download report below) if used with Silwet L-77 Super Spreader (or equivalent OMRI Approved spreader/sticker).
The company that formulates LockDown herbicide is small and orders for the bio-herbicide fungus have to be made in advance so that it can be “brewed” and ready to apply. Cost is less than $15 an acre. It is a bioherbicide with nothing but fungal material in the product. Certified organic operations would need to get approval from their certifier before using. (LockDown label below)
If any organic rice farmer is interested in applying LockDown Herbicide to control Northern Jointvetch and/or experimenting on Hemp Sesbania control, please let me know. We will be getting an order ready and picking up the Lockdown Bio-Herbicide for growers later this spring.