Agriculture Reference
In-Depth Information
The term “action threshold” is at times used
synonymously with the term “economic threshold”.
Unfortunately, the scientific process to develop
pest densities associated with the economic
injury level concept takes a great deal of effort
and resources. As a result, many potato pests are
without a widely accepted and adopted eco-
nomic threshold. Often, practitioners must rely
on past experience to develop economic thresh-
olds for their farm or region in relation to the end
use and value of their crop.
Management of arthropod pests of potato
varies significantly based on the pest, growing
region, end use of the crop, and potential crop
value. Below, we discuss general concepts rela-
tive to good cultural and chemical pest manage-
ment as a component of IPM.
wireworm. When potatoes are planted following
grass or long-term pasture, wireworms are more
likely to be a pest than if the potatoes followed
maize, sugarbeets, and many other crops.
Proper planting depth and post-planting
tillage will minimize surface-exposed tubers,
leaving them less vulnerable to infestation from
insects like the potato tuberworm. Potato tuber-
worm damage can also be reduced by decreasing
the time between vine kill and tuber harvest.
The shortened pre-harvest interval does not
allow tuberworm larvae adequate time to move
from the foliage to the soil, where they can infest
tubers near the surface. Although cultivar choice
has a limited impact on reducing pest-related
issues, some cultivars may fare better than others
when pressured by certain pests. Potato cultivars
with large canopies may be able to sustain more
damage from chewing-type insects than those
with small canopies. Cultivars that mature early
may be harvested before insects like the potato
tuber moth become an issue during a given sea-
son. Planting and harvest timing with all culti-
vars should be used when possible to reduce pest
abundance and infestation issues. Utilizing cul-
tural management of pest reduction is import-
ant, but it must often be combined with pesticide
use under typical, modern farming systems.
Cultural management practices
Use of high-quality, certified potato seed, free
from insect pests or insect-vectored pathogens, is
essential in reducing pest build-up. Insects like
potato tuberworm can be spread across the
world quickly and easily via shipment of larvae-
infested seed. To minimize seed-related insect
spread, the commercial producer should visit the
seed grower's farm during the growing and storage
season prior to a seed purchase. In conjunction
with regional certification, personal inspection
of the seed grower's fields and storage units can
contribute towards the movement of clean seed.
Following planting and harvest, all growers
should dispose of waste potatoes properly. Deep
burial or rapid destruction and removal of waste
potatoes will reduce the chances that a tuber-
borne pest such as the potato tuberworm will
survive and infest potatoes in the future.
Crop rotation is also important in reducing
potential pest damage. Because insects like the
Colorado potato beetle overwinter as pupae in
the soil, potatoes planted back to the same field
or in close proximity to that field during con-
secutive years may experience unnecessary
pressure from the pest. By planting different
crops each year in a particular field, high pest
populations may be avoided. One must also con-
sider, however, which rotational crop to plant
prior to producing potatoes. The previous crop
may impact the next potato crop negatively by
providing food and safe haven for pests like the
9.5
Chemical Management
Due to the combination of risk-averse producers
and the high crop value of potato, insecticides
are oftentimes used to manage insect pests.
Insecticides should be applied according to label
recommendations, adhering to proper timing,
application rates, use of surfactants when ap-
propriate, and safety recommendations for hand-
lers and bystanders. Judicious use of pesticides
should be practiced to avoid the development of
insect populations that are resistant or tolerant
to specific pesticide compounds. Resistance or tol-
erance to a pesticide simply means the pesticide
compound intended to result in insect mortality
no longer causes mortality at the concentration
or rate it did originally. Resistance typically occurs
by making multiple applications of the same
compound to successive insect generations. Such
repeated applications select for naturally occur-
ring genetic mutations in the insect population,
which confer tolerance or resistance to the
