NDSU Crop and Pest Report

Plant Science


ISSUE 13  July 24, 2003

POTATO LEAFHOPPER IN ALFALFA?

I suggest producers monitor seeding-year stands of alfalfa for potato leafhopper since several calls indicate that leafhoppers are more severe this year than most. Most clear-seeded stands and companion-crop-seeded stands harvested for forage have been harvested for the first time by now. Watch the regrowth for signs of leafhoppers. The first signs of potato leafhopper problems is the development of wedge-shaped yellowing of the tip of leaflets. This "hopper burn", if severe, causes stunting of plants, yield loss, plant vigor loss, and loss in hay quality (especially protein content). Hopper burn is sometimes confused with drought stress and not recognized early.

Potato leafhoppers do not over winter in this area but fly in from the south. Normally leafhoppers do not arrive early enough to be a problem in the first harvest of the seeding-year, but are a problem in eastern North Dakota about once in three years on the second harvest of clear-seeded stands or the regrowth following harvest of a companion-crop-seeded alfalfa. This year the leafhopper arrived earlier than normal and caused some damage in the first harvest so I anticipate greater problems in the second harvest.

Potato leafhopper is rarely a problem on established stands harvested on a timely schedule because first harvest occurs before the leafhopper arrives. Alfalfa harvest very late frequently is more yellow-appearing than early harvested alfalfa, which is frequently associated with leafhopper damage. Since leafhoppers are more severe this year, watch the established stands also.

The economic threshold for application of an insecticide ranges from 0.5 to 2 leafhoppers/sweep for 6 to 12 inch stems, respectively. If an insecticide is warranted, see the following web site for various alternatives:

http://www.ext.nodak.edu/extpubs/plantsci/pests/e1143w15.htm

Dwain Meyer
Extension Specialist, Forages
dmeyer@ndsuext.nodak.edu

 

NEW ROW CROPS AND OILSEED WEB SITE:

A row crops and oilseeds website is now available on the NDSU Plant Sciences web page. The sites address is:

http://www.ag.ndsu.nodak.edu/plantsci/rowcrops/main.htm  

There is still some refinement and editing to be done but should be useful to growers and others interested. Crops included on the site include: Soybeans, Corn, Dry Edible Beans, Sunflower and Canola. Many links to other good crop production sites can also be found at this site. Also the site of the North Dakota Small Grains web site is:

http://www.ag.ndsu.nodak.edu/aginfo/smgrains/

 

CANOLA - OPEN POLLINATED, SYNTHETICS AND HYBRIDS

Many times the question comes up on what is the differences in various types of canola cultivars being grown in North Dakota. Here are some simple descriptions on the various types.

OP or open pollinated varieties are varieties selected from one plant and then increased with like plants. Usually they are increased with some isolation and are then a OP or cross pollinated variety of similar genetics. They usually are not pure lines as some outcrossing can occur. They usually are uneven in height, can be a little less uniform in flowering and maturity in a given field. OP do have some yield stability under stress (moisture or heat) better than some hybrids.

Synthetics: These are varieties usually developed from random crosses within a closely related group of plants such as 6 to 10 plants. The seed is then bulked and continued to be increased. It is somewhat like a poor sister hybrid. The most important step in development of a Synthetic is the selection of the parent plants. Generally the seed of a synthetic is cheaper to develop than a Hybrid. The canola varieties that are synthetic types seem to yield and perform quite well. Usually under certain stress situations such as extreme hot or dry conditions.

Hybrids: These are cultivars formed by crossing of two inbred lines which have been self-crossed to insure their genetic purity. When crossed to make hybrid seed these cultivars will express the best of the genetics of the cross known as hybrid vigor. Not all inbreds with do this and the poor crosses are discarded with only the best hybrid fits used in development of Hybrid seed. We find either the Roundup Ready or Liberty Link gene inserted into our Hybrid canola's. However, there are a few OP's that are RR Ready. Also with Hybrids we find more uniformity than with both the OP or Synthetics. Higher yields, more uniform flowering and maturity.

Duane R. Berglund
NDSU Extension Agronomist
duane.berglund@ndsu.nodak.edu

 


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