NEWSLETTER ARTICLES

Franklin Laemmlen, Ph.D., County Director and Vegetables/Pest Management Advisor

From our Central Coast Agriculture Highlights newsletter -- April 2001 issue.

INJECTING AIR INTO DRIP LINES MAY INCREASE YIELDS

A recently reported study from California State University, Fresno, indicates that bell peppers grown using buried drip tape had a 33-39% increase in yield when air was injected into the drip line. The report is preliminary, and the research is ongoing.

The research was done on a one-third acre plot. Drip lines were buried 5 to 6 inches, and runs were 190 feet long. The treatments were subsurface drip irrigation (SDI) untreated and SDI with 11% by volume injected air. The drip tape was Toro-Ag blue stripe drip tape, rated 0.34 gallons per minute per 100 feet under 8 pounds per square inch pressure. Air was injected into the tape via manifold, using a Mazzei model 584 differential pressure injector. The data suggest that "the major effect of the injected air is within the first 150 feet of the drip tape inlet." The effect appears to be from the increased oxygen (aeration) provided to the root system (i.e., well aerated soil).

So far the research is confined to small plots and short (relatively) drip tape runs, but the yield increase is dramatic enough that keeping track of this research will be worthwhile. The system is simple. Growers with small acreages could very easily, and at low cost, adapt this technology to existing buried drip systems.

USEFUL WEBSITES FOR AGRICULTURE PRODUCERS

The Internet can be very useful as a source of current and historical information. The websites for agriculture continue to increase, and existing sites contain more information. The following sites may be of interest to Central Coast growers.

Pesticide Registration http://www.cdpr.ca.gov

U of Calif. Directory http://danr.ucop.edu

Santa Barbara County Cooperative Extension http://www.sbceo.k12.ca.us/~uccesb1

Weed Information http://wric.ucdavis.edu

Information of Interest to Small Farms http://www.sfc.ucdavis.edu and http://www.usda.gov/oce/smallfarm/sfhome.htm

Integrated Pest Management http://www.ipm.ucdavis.edu

Vegetable Information http://vric.ucdavis.edu

Postharvest Information http://postharvest.ucdavis.edu

Fruit & Nut Crop Information http://fruitsandnuts.ucdavis.edu

Sustainable Agriculture Information http://www.sarep.ucdavis.edu

Ornamental Horticulture Crops Information http://ohric.ucdavis.edu

Florida Vegetable Information http://edis.ifas.ufl.edu

Oregon Vegetable Information http://www.orst.edu/dept/hort/hortcrop.html

Florida Vegetable Prices http://gnv.ifas.ufl.edu/~marketing/market.html

Weather Information http://www.weather.unisys.com/

CULTURAL PRACTICES TO HELP MANAGE SOIL INSECTS IN SPRING VEGETABLES

Growers are aware of the benefits of crop rotation to manage soil productivity and to control pest problems such as soil-borne pathogens, nematodes, and weeds. It is less commonly known that crop rotations, if properly managed, can help reduce insect pest problems.

When double and triple cropping, several insect problems can occur due to inadequate time allowed for complete decomposition of crop residues before starting the next crop. This problem can occur due to inadequate planning, delays in crop destruction due to equipment failure or weather conditions. Regardless of the cause, non-decomposed crop residues in seed beds attract seedling insect pests that can cause stand thinning or complete stand loss in portions of the field.

Close rotation of vegetable crops, especially broccoli, cabbage, cauliflower, and Chinese cabbage, without allowing time for residue decomposition can result in damage due to seedcorn maggot or astigmatic soil mites.

Seedcorn maggot is one of the most common insect pests attacking germinating vegetable seeds and seedlings. Seedcorn maggot is a widely distributed insect pest in the temperate regions of the world. Injury to plants results mainly from the maggots feeding on the sprouting seed or on seedlings. This pest attacks many vegetable crops. The maggots burrow into seed, feed on endosperm, and often leave only a hollow shell. Attacked seeds, which germinate, often fail to form true leaves. In seedlings the stem and roots are injured, causing the seedling to be stunted or break over near the soil line.

An abundance of decaying crop residue in fields at planting attract seedcorn maggot flies.

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