ATTRA Question of the Week

G.H.
Idaho

Answer: Thank you for your recent request for information from ATTRA, the National Sustainable Agriculture Information Service regarding weed management in your newly planted asparagus.

As you are finding out weed management is critical to growing asparagus, since it is a perennial crop and tillage options are limited once the asparagus is planted—especially during the spear and fern stages of production. I usually recommend a strict cover-cropping strategy before the asparagus goes in, but since you have existing plants I will recommend a few options.

The weed management strategies are different for annuals than perennials. I will make some recommendations based on each kind of weed.

Annual weeds will be easier to control in your asparagus crop than perennials. At this point, hoeing and hand weeding may be your best option, but shortly after this, you can apply a mulch either living or straw to help keep down the weeds. A living mulch of oats and peas could be seeded in the fall, then allowed to winterkill and provide a cover to keep the weeds at bay. If you choose to use straw, be sure that it is indeed straw and not spent hay, which can make your weed problem worse.

Another option for annual weeds the following spring before the asparagus begins to emerge, is to use a flame weeder. This product can efficiently and effectively help with weed management if done early on. It is important that you flame weed before the tips emerge. As a general rule, flame weeding is most effective against annual broadleaf weeds, moderately effective against annual grasses, and a poor option for perennial weed management.

For perennial and annual weeds during spear and fern production weeder geese are an option. In order to make cost comparisons between geese and other weed control methods, you will need to keep a record of the time spent moving, feeding, and watering the geese. A good book on raising geese and using weeder geese is The Book of Geese available from many sources, including Metzer Farms. This book along with more information on this topic is available by visiting their web site:
http://www.metzerfarms.com/weeder.htm

Another option for perennial weeds, besides hand-weeding, is to use a burn-down organic herbicide such as acetic acid or clove oil. These products can be most effective when the perennial weeds are just emerging and the key is to use it every time you see them re-emerging to exhaust their root reserves. This may need to be done several times in the season. I would also encourage you to look ATTRA’s Organic Asparagus Production publication.