In strawberry and other crop field soils, growers and PCAs may occasionally see small “worms” wriggling around and near the roots and crowns of plants and sometimes around ungerminated seeds. Concern is sometimes expressed that these worms might be plant parasitic nematodes that could damage strawberry or other crops. There is good news here: if one is able to see these worms without using a hand lens or other magnifier, these worms are not parasitic to plants.

Worm samples submitted to our UCCE offices over the years have all turned out to be a type of soil and water organism called an oligochaete worm (which is in the taxonomic group Annelida). These small worms are large enough to see without magnification (Fig. 1), are whitish to translucent in appearance, and move vigorously when disturbed. Examination with a microscope is needed to confirm the identification; the worm body is made up of segments (Fig. 2), with each segment bearing small external spines or seta (called chaeta) (Figs. 3 and 4). Oligochaetes are much larger than the parasitic nematodes that attack plants (Fig. 5).

Closely related to earthworms, these small oligochaetes are found in wet areas such as puddles of standing water and moist soils. Like earthworms, they feed by ingesting sediment and soil particles and digesting nutrients from organic matter and bacteria. Oligochaetes may therefore be found in large numbers in soil around organic substrates, rotting plant materials, and other food sources.

Molybdenum (Mo) is the minor of the minor nutrients and usually doesn't show up in my strawberry and caneberry tissue samples at a concentration higher than 1 or 2 ppm.  Molybdenum exists in the soil as molybdate ion (MoO₄ ^-2 ) and in most soils one won't find more than an ounce per acre.

Low as the concentrations in the soil and plant tissue may be, molybdenum is more important than you might think. 

Mo functions in nearly all nitrogen transformations in the plant which result in proteins.  If you recall from your high school biology, one functional group of the amino acids is the amine, which of course contains nitrogen.  In short, the plant takes up nitrogen as nitrate, which is then converted to ammonium, then to the amine containing amino acids followed by their combination to form proteins. Absent molybdenum, nitrate is simply taken up by the plant, not converted to protein and results in a visibly weaker plant.

Molybdenum become substantially more soluble (ie available) as the pH of soil rises, and as such the first approach of the grower or agricultural practitioner to addressing the admittedly rare event of Mo deficiency would be to raise the soil pH. 

An additional problem concerning Mo can crop up from the use of sulfur containing fertilizers and soil amendments (for example, think ammonium sulfate [(NH₄)₂SO₄] and gypsum [CaSO₄^-2]).  Sulfate ion (SO₄^-2 ) and molybdate ion (MoO₄ ^-2) are chemically very similar to one another and as such compete with one another for absorption by the plant roots.  So lots of sulfate in a soil (as can be common in a soil which is acidic), equals more sulfate taken up by the plant and proportionally less molybdate.

The concluding statement I am going to make here is that while molybdenum deficiency it is rarely an issue (I've never seen it personally) in Central Coast grown strawberries and caneberries, I still feel knowledge of its purpose and causes of deficiency are important for growers and agricultural practitioners of this area.

Much of the information in this post comes from the article "Molybdenum in Vegetable Production" in the periodical "Vegetables West" August 2005 (pp 14-15) by Dr. Tom Ruehr from CalPoly.

This comes from my colleague Bernadine Strik up at OSU:

Oregon State University will be offering another Blueberry School on March 16-17, 2015 in Corvallis. Early registration for reduced rates ends on Feb. 5, 2015. http://osublueberryschool.org/

This two-day blueberry “school” is intended for both new and experienced blueberry growers, farm managers, crew leaders, advisors, packers/shippers, and consultants. Key issues addressed include blueberry markets, how you might be more successful in tight labor or volume markets; which cultivars are easiest to grow and are in most demand; how to establish new acreage using cutting-edge methods; how to best manage existing acreage to maximize returns of high-quality fruit; basic information on blueberry plant physiology; nutrient management programs; irrigation and fertigation practices; use of organic amendments and mulches; using weed mat as a mulch; machine harvest; pruning, maximizing pollination; and viruses, diseases, insects, weeds, and vertebrate pests. Information throughout the program will address the needs of conventional, transitional, and organic growers. For more information see our draft agenda posted on the web site.

Simultaneous interpretation for Spanish speakers is planned with sponsorship funds generated. If you'd like to sponsor this event, please contact Bernadine Strik (bernadine.strik@oregonstate.edu)

Announcing the 2015 Annual Strawberry Production Research meeting on February 20. 

Please note that it's a few weeks later than usual because of the North American Strawberry Grower's Association meeting from February 3 to February 6 (which by the way I strongly recommend - just looked at the schedule this morning and it is chock a block with good speakers and excellent content). 

Additionally, the location will be back at the Elk's Lodge on 121 Martinelli Street in Watsonville.

See you there!