Longspine sandbur (Cenchrus longispinus)

This week we are going to talk about longspine sandbur. This is a nasty plant that blends in with other grasses, quietly waiting for an unguarded foot to stick into. Yes, true to its name, this noxious weed has spines on it. Longspine sandbur is an annual grass, so it spreads only through seeds rather than a rhizome system like perennial plants. Much like puncturevine, these seeds can stick into tires, fur, and clothing. This noxious weed can be found in disturbed areas such as waste areas, roadsides, field edges, etc.

So how do we control this nasty invader? Because this plant is an annual, mechanical control can be effective. This would include mowing, tilling, pulling, etc. One thing to keep in mind with mowing, however, is that although it can slow down seed production, many plants have the ability to grow shorter than the mower cutting height. This means that these plants can bloom and seed out under the height of where they were last cut.

Herbicides are also effective on longspine sandbur, although because it is a grass, the herbicides must be non-selective in nature, which means damage can occur to desirable vegetation such as grass. Many of our noxious weeds are easy to spot once they get any height to them, as they are distinctive. However, like mentioned above, sandbur will blend in with grasses which makes it tough to spot.

The burs on longspine sandbur can get stuck in clothing and reduce the value of wool. If you see this plant hanging around, be sure to call the authorities (our office) at (509) 754-2011, Ext. 4710, to come deal with these perpetrators.

Stay safe and enjoy your time outdoors.

Soil testing

By Mark Amara

WSU Grant-Adams Area Master Gardener

Once soil type is identified, the gardener has some basic information about its characteristics. Building and maintaining soils are important to be able to produce healthy crops. Soil testing is an easy way to get some baseline information about crop needs and should be done at least every three to five years. Though soils test kits are available through garden centers, the most accurate determinations are made by soil testing firms who perform specialized laboratory analyses and offer specific fertilizer recommendations based on the results. Though there is a whole gamut of testing that can be done, gardeners should ask for nitrogen, phosphorus, potassium, sulfur, boron, zinc, copper, soil pH (acidity or alkalinity), and organic matter.

Look for more on soil testing next week.

Soil testing “kits” are provided by several of the soil testing firms in the area. These kits consist of pint - quart size bags which the gardener fills and labels with pertinent identifying information.

The rules of thumb for taking samples for testing include: Sampling where crops are being planted or have been planted only, rather than taking soil from paths or other areas outside the garden.

Try to sample representative areas of the garden and stay away from poorly drained areas or previously used nutrient rich areas like the compost pile, barnyard or manure heap.

Using a clean bucket, collect samples from as many as a dozen spots in the garden to a depth of one foot (though deeper sampling is suggested for deeper rooting crops if that is typical for your situation). Make sure the tools used are also clean to avoid any sample contamination. Thoroughly mix the soil in the bucket and take as much as possible to fill the sample bag. If the garden is large or you have distinct areas that you think may have different needs, consider testing in those areas too. However, that will mean extra costs.

Be sure to avoid including organic matter in the bags (lumps of compost, manure, leave, twigs or clippings) as this can skew the sampling.

However, gardeners are always advised to talk to the preferred soil testing firms for specific directions or to help decide what tests to run and, of course, to get a cost list. It takes a few days to get results. Tests are quantified using standardized professional standards by technicians working in pristine laboratory environments. The Master Gardeners can help you locate soil testing laboratories that will perform soil tests for home gardeners in your area.

Typically, Grant and Adams Counties soils are low in nitrogen and sulfur, both of which are soluble in water which means that these nutrients can leach away rather quickly. Some of the trace elements like boron, zinc, and copper are important to crop health on a commercial scale but may not be reflected as much in home gardens. Many of our soils are on the alkaline side of the pH scale. If pH gets much above 8.0 gardeners can consider amending them to bring the pH closer to 7.0 which is considered neutral. High or low pH can tie up nutrients making them unavailable to plants so it is important to monitor and find ways to maintain or improve conditions often. Our soils are typically low in organic matter. In a native condition, organic matter is at 1% or less. Ideally, the higher the organic matter, the more healthy and productive soils can become so improving it constantly with copious additions on an annual basis by incorporating crop residues, adding straw or alfalfa or other untreated materials like leaves and grass clippings, or planting cover or green manure crops is highly recommended.

Adding manures of one kind or another over time should be watched as they can accumulate nutrients to excessive levels. Moderate diverse applications are recommended. For example, when cow manure is added year after year to build organic matter, phosphorous which is one of its components, can reach levels which may be too high for many crops to endure. Then, it may be necessary to find ways to ameliorate these conditions like growing crops which help utilize the nutrients and help moderate its levels or avoid fertilizers with phosphorus. Similarly, growing crops on high pH soils can be done without amending it if you know what will tolerate higher pH. More people seem to be planting blueberries in eastern Washington. For that crop, soils must be amended to bring the pH down into the acid range because the plants will not produce otherwise.

For answers to gardening questions, contact the Master Gardeners at the WSU Grant-Adams Extension office at 754-2011, Ext. 4313 or email your gardening questions to ga.mgvolunteers@wsu.edu. Visit our web page at grant-adams.wsu.edu.