ISSUE 2 May 13, 1999
SPRINGTAILS FEEDING ON BEETS ?
Early in the 1998 season, there were problems with springtails
affecting seedling beets. With the current
wet and cool conditions, feeding and losses may occur again due to these insects. Some concerns of injury
have already been raised for fields where granular insecticides were not used.
Springtails are very common soil dwelling insects. They are white,
tiny (1/32 to 1/16 inch in length),
are very active, live and feed below ground, and require very moist soil for survival. The particular species
that has injured sugarbeets is Folsomides parvulus. Feeding injury appears as discolored lesions on the
tap root. When you pull up soil around the base of a dying plant, you may see them move for only a second
or two before they disappear back into the soil. Very good eye-sight is required for finding this insect.
To find springtails in the soil, take a shovel full of moist soil and throw it in a bucket of water. Springtails
will float to the surface.
Springtail which injures sugarbeets
Last season, fields that experienced problems with springtails had
very moist soil and high residue,
such as last years small grain straw. Springtails feed on fungi and bacteria associated with rotting organic
matter in the soil. When the springtail densities reach several thousand per square foot in moist soil and
the fungi and bacteria happen to be in contact with the root surface, feeding injury occurs.
The use of granular insecticides at planting should control
springtails. Last year there were reports
that granular insecticides were not effective in controlling springtails. However, there is research that
indicates springtails are very susceptible to organophasphate insecticides. If control failed in spots last
year, suspect leaching of the insecticide in coarser textured soils. It was observed last year, that fields
with injury and no granular insecticide, the problem continued as long as soil moisture remained high.
COOL, RAINY WEATHER IMPACTS INSECT PEST POPULATIONS?
Since insect development is usually closely related to temperature,
development has been delayed
along with the crop planting.
Grasshoppers? Cool, wet weather prevents premature
hatch of young grasshoppers in the early
spring. Since little or no grasshopper activity has occurred in the state, this weather will cause little
mortality of young grasshoppers. However, grasshopper numbers were generally lower last year and
this should be reflected in this years numbers. If ND has a warm, dry, late spring, this will promotes
uniform hatching time and good weather conditions for feeding.
Crucifer Flea Beetle? Emergence of flea beetles has
been delayed. When air temperatures warm
up to 68"F, flea beetle activity should increase rapidly. Unfortunately, this will coincide with the planting
and emergence of canola. Fields should be scouted closely during seedling stage.
Wheat Midge? The wheat midge are overwintering in
larval cocoons and well protected from the
weather. Limited degree day accumulation has occurred this past week - average of only 5 degree
day units per day in Minot! Thus, midge development is being delayed along with the wheat planting.
Wireworms? Wireworms can readily move around in the
soil and can avoid the wet areas. As the
soil dries and warms to 50-55"F, wireworm larvae will feed within 6 inches of the soil surface.
Wireworm infestations are commonly found on the sides of ridges and where grasses, including small
grains, are grown. Wireworms are another soil insect whose damage is more common when seed
germinations is delayed by cool soil temperatures.
Cutworms? Cutworm development will be delayed
especially for the later season cutworms like
pale western, darksided, and red-backed cutworms, that overwinter as eggs. All hatching and feeding
activity is slowed but will resume when soils warm.
Plant Protection Specialist
TOPS-MZ-GAUCHO POTATO SEED-PIECE TREATMENT, Special Local Need, 24(c) Registration
The North Dakota Department of Agriculture issued ND SLN Number ND
May 6, 1999. The Bayer Corporation label allows for application of Tops-Mz-Gaucho to potato
seed-pieces "to aid in the control of the potato aphids and Colorado potato beetle, Fusarium
(dry rot), Rhizoctonia (black scurf and stem canker), Helminthosponium solani (silver scurf), and
to help reduce the spread of Phytophthora infestans (late blight) resulting from seed-piece to seed-piece
These products are federally registered, individual pesticide
products. The SLN allows them to be
applied as a mixture onto the cut potato seed-pieces. All precautionary statements from the section 3
labels and the SLN labels must be followed. The SLN label must be in the possession of the user for
Though this label is currently in effect in North Dakota, EPA has a
90 day comment period to either
accept or reject this state registration, which could impact the future use of this combination.