Ramsey County Ag Column

By Bill Hodous

June 2, 2008

Howdy!!!

A good shot of rain would really be nice, within reason.  We do have some soybeans and drybeans along with some Canola laying in dry dirt.  I checked the NDawn station (Crary) this morning and as of this morning we about 72 GDD behind the norm for corn.  With rain in the forecast a warm up is unlikely so will likely stay behind normal for the upcoming week.  I was in a tractor over the weekend and noticed weeds in full swing, to include wildoats.  As we get ready for the upcoming spraying season remember to not only follow and read the label, of the herbicide you are applying but also wear your protective equipment.  My wife works in the E.R. and does not like seeing people she knows that made bad choices.

Nodulation in Pulse Crops - A few producers have expressed concern about how well the rhizobia bacteria in the pulse crop inoculants has survived given the dry soil conditions that some of the crop went into this spring.  The cool conditions this spring should have helped the rhizobia survive, but producers should check pulse crops for nodulation in the next few weeks.

Nodules in pulse crops don’t begin forming until about the 3 or 4 node stage, which is approximately 3 weeks after emergence.  Nodules will form on both the primary root and lateral roots.  Healthy nodules actively fixing nitrogen for the plant are pink or red inside.  The absence of nodules or white, brown or green nodules indicate that nitrogen-fixation is not occurring.  If the plants appear yellow and/or no healthy nodulation is observed on the roots by the 5 node stage, then it is suggested to get the field top-dressed with nitrogen as soon as possible as a rescue treatment.  Nitrogen fixation only occurs for 3 to 4 weeks, so every week counts.

When checking pulse crops for nodulation, do not physically pull the plants since root hairs will slough off along with the nodules you are checking.  It’s best to dig plants up with small spade or trowel.  The roots should be shaken gently to remove the soil or can be soaked and washed in a pail of water or taken back to the farm and sprayed carefully with a hose to get a better observation of the roots and nodules forming.  It is suggested to check and sample 5 different locations of the field for nodule development.

Alfalfa Weevil 

Larvae

Historically, alfalfa weevil larvae are not a wide spread concern in North Dakota. The light green larvae have a white stripe down the center of the back. They feed in the terminal buds of the growing alfalfa. They may be found in rolled up leaves at the growing tip of the plant. Feeding injury appears as small, circular holes in leaves. As larvae increase in size, feeding injury is more evident. Severely damaged fields take on a silvery appearance due to browning of injured leaf tissue.

Alfalfa Weevil Management:

If alfalfa weevil infestations are observed, one of the best strategies is to cut fields for hay early. After cutting, monitor carefully for signs of damage or delayed re- growth, particularly in the swath area where larvae may be concentrated. When early cutting of the crop is not possible, treatment should be considered when 30% of the plants show feeding damage and larvae are still present. To sample, inspect 20 stems from each of 5 sites in the field, recording the percent damaged plants and whether larvae were found. NOTE: When spraying legume fields, apply insecticides between 8:00 p.m. and 8:00 a.m. to protect the local bee population. Never spray fields in bloom.

524 4th Ave #5, 2nd Floor Ramsey County Courthouse
Devils Lake  ND  58301
701-662-7027
email - ramsey@ndsuext.nodak.edu