Resource Guide for Organic Insect and Disease ... - Cornell University

Organic Insect and Disease Control for
Umbelliferous Crops
72 Organic Resource Guide
INTRODUCTION
This group of crops belongs to the family Umbelliferae or Apiaceae. This large family
is commonly referred to as the umbel family because of the distinctive, umbrella-like
inflorescence. Many members of the family are biennial root crops, and flowering is not seen
during crop production (e.g., carrots and parsnips). Other umbelliferous crops are grown for
their stalks or foliage and are not usually grown to flowering stage, including celery, parsley,
dill, cilantro, and lovage. Others, like coriander (cilantro), dill, caraway, cumin, and fennel,
are grown for their seeds. In this family, the fruit (called a schizocarp) splits into two parts at
maturity, each containing a single seed.
I. INSECT CONTROL__________________________________
CUTWORMS (many species)
Cutworms are occasional early-season pests of carrots and other umbelliferous crops. In some
years, they cause major losses, while in other years, there are no losses at all. Cutworms are
the larvae of approximately a dozen different species of night-flying moths. They are greasylooking
caterpillars that have a habit of curling into a “C” shape when disturbed. Most species
that attack carrots overwinter as partially grown larvae, so they become active very early in the
spring when the carrots first germinate and are very susceptible to damage. Cutworms hide in
the soil during the day and feed at night. Some species feed and cut off young seedlings at the
soil surface, while others may climb and feed on leaves.
Cultural Control:
1. Since most species lay their eggs on vegetation in late summer or fall, keeping fields
clean of weeds and crops in the fall helps. This advice is counter to recommendations
to keep soil cropped in the fall, so management decisions should be based on how
severe the problem is. Fall plowing exposes larvae to birds and other predators.
2. Alternatively, cultivating fields in the spring, after vegetation has appeared and grown
a few inches, can starve cutworms before crops are planted. In most areas spring
cultivation is not practical for early season production. In regions that allow for delayed
planting, a few shallow cultivations during this “starving period” can starve cutworms
and expose them to birds and other predators.
Materials Approved for Organic Production:
1. Entomopathogenic nematodes have shown good efficacy when environmental
conditions are favorable (warm, moist, but not soggy soil). Steinernema carpocapsae
has been shown to be very effective against cutworms, although reports are not
specifically for carrot production. Success with nematodes depends on proper
application methods. Irrigation may be necessary to keep the soil moist for at least
two weeks after application. Be sure to carefully follow the instructions from the
supplier.
2. Baits - Spinosad or Bt will kill the caterpillars, but getting the pest
to consume the insecticide as a foliar application before significant
damage is done is difficult. However, farmers have reported good
results using these materials in baits. The bait is spread on the ground
near the plants or prior to planting to disinfest an area.
a. Spinosad - Seduce (OMRI Listed) is a new, ready to use
formulation bait that has shown promising results against
cutworms.
b. Bt - A bait made from Bt is often recommended and has
received good reports from some farmers. The following