One Thousand Questions in California Agriculture Answered

by Edward J. Wickson

I have in about four acres of watermelons, and there seem to be lice and a small gnat or fly, and also some small green bugs and white worms on the under part of the leaves, which seem to be stopping the growth of the vines, making them wilt and die. They seem to be more in patches, although a few on all the vines. Can you please tell me what to do for them?

Melon lice are very hard to catch up with after you have let them get a start. Spraying with oil emulsions, tobacco extracts, soap solutions, etc., will all kill the lice if you get it onto them with a good spray pump and suitable nozzles for reaching the under sides of the leaves. The gnats you speak of are the winged forms of the lice; the white worms may be eating the lice; the "small green bugs" may be diabroticas. If you had started in lively as soon as you saw the first lice you could have destroyed them in the places where they started. Now your chance lies largely in the natural multiplication of ladybirds and the occurrence of hot winds which will burn up the lice. It is too late probably, to undertake spraying the whole field.

Wire Worms.

Is there any way to destroy or overcome the destructive work of the wireworm, which I find in some spots takes the lion's share of crops, such as beans, potatoes, onions, etc.?

We do not know any easy way with wire worms. Nitrate of soda is believed to kill or repel them, but you have to be careful with it, for too much will either over-stimulate or kill the kill; about 200 pounds per acre, well distributed, is the usual prescription for the good of the plants. Wire worms can probably be killed with carbon bisulphide, using a tablespoonful poured into holes about a foot deep, three or four feet apart. The vapor would permeate the soil and kill all ground insects, but the acre-cost of such treatment must be measured in its relation to the value of the crop. The most promising policy with wire worms is rotation of crops, starving them out with a grain or grass crop and not growing such crops as you mention continually on the same land.

Bean Weevil.

How can I keep certain insects from getting into my dry beans? I have finished picking the crop. Every year a little, short, stubby beetle gets in them before spring and makes them unfit for use.

You have to do with the bean weevil. The eggs are inserted by the insect while the beans are still green in the pods; subsequently the eggs hatch and the worm excavates the interior of the ripened beans. The beans can be protected after ripening by heating carefully to 130° Fahrenheit, which will destroy the egg, or the larva if already hatched. Of course, this heating must be done cautiously and with the aid of a good thermometer for fear of destroying the germinating power. The work of the insect can also be stopped by putting the beans in a barrel or other close receptacle, with a saucer containing about an ounce of carbon bi-sulfid to vaporize. Be careful not to approach the vapor with a light. After treatment for one-half hour, the cover can be removed and the vapor will entirely dissipate. This is a safer treatment than the heating. Similar methods of control can be used on other pea and bean weevils.

Slugs in Garden.

Can you advise me how I can get rid of slugs in my garden?