Hi. I wanted to ask if you have any advice on how to build garden boxes that will not allow snails to climb up on the vegetables?
— Thanks, L. P.H.
I do not know of any specific construction that will keep snails out; perhaps some of the readers can help. My method of restricting slugs and snails is the use of copper. Several years ago, University of California proved that copper provided an effective barrier for snails. Sheets of copper 4-6 inches wide were wrapped around the trunks of citrus trees like a collar; consequently, snails would not cross it. Whether it’s a tree trunk or fastened to the wood of a garden box, copper provides an excellent deterrent for snails and slugs.
A less expensive alternative to the copper sheeting is the application of a liquid copper solution. One product is called Copper Bordeaux, a mixture of copper sulfate and lime. The product is mixed with water into slurry; exact ratio of water to powder is not critical although a 1:1:10 ratio is often used, i.e., copper sulfate (lb.) to lime (lb.) to water (gal). Sometimes a dash of white latex house paint is added to help preserve the solution under rainy conditions. This solution can then be painted on wooden boxes, greenhouse table legs, or a barrier that surrounds the garden. Rain presents a problem with this method as it eventually washes away the solution. In an area with under 20 inches of rainfall per year, the copper solution applied to tree trunks usually lasted a year. If this method is used in areas of high rainfall, some type of covering would be needed to help protect the exposed copper surfaces.
Dry ash or other abrasive powders such as diatomaceous earth can be a barrier for snails and slugs.
These barriers lose their effectiveness after becoming damp, and therefore, are not useful in wet or very humid climates. In addition there are snail baits, organic and safe for pets, which can be applied around vegetables.
I have some pilau maile coming up in my yard. It hasn’t been there very long, and I want to get rid of it right away. What is the best chemical to spray?
— Thanks much, B.G.
Chemical control is one of the most effective means for controlling maile pilau. However, because of resprouting, single applications usually do not provide complete control; follow-up applications are necessary. In your case, if the plants are relatively young, one application may do. The herbicide to use is one with the active ingredient, triclopyr, sold as Crossbow, Garlon, Pathfinder; they are rather expensive. A non-ionic surfactant is recommended at 2 teaspoons per gallon of spray solution. A 2 percent to 3 percent solution of glyphosate (Roundup, etc.) may also be effective, although some report it is not. If you have Roundup, you may want to try it first before purchasing triclopyr.
Presently biological control agents are being collected in Japan and Nepal. It is hoped that these ‘good guys’ which include a leaf and root feeding chrysomelid beetle will be able to help control the spread of this weed pest. Maile pilau (Paederia foetida) is a woody vine that is able to grow 30 feet in length. The vines can engulf and cover trees and shrubs. The weight of the vine mass climbing over vegetation can cause branches or entire trees to break or collapse.
When crushed, the leaves release a foul odor. Foetida (species) is Latin for stinky.
I will again teach the Vegetable Gardening Class on Saturday, May 12, 9:30am to noon. Call UH-Hilo Continuing Education at 974-7664 or register online at: http://hilo.hawaii.edu/academics/ccecs/registration/
Hilo resident Nick Sakovich is a professor emeritus of the University of California. E-mail your questions to Sakovich at askthegardenguy@earthlink.net.
