For Pepper Growers, Built-in Nematode
ARS geneticist Richard Fery (left) and technician Floyd Maguire examine the
root system of a pepper plant showing severe galling from the southern
After many years of fighting, the pepper war between farmers and nematodes
continues to rage on. Farmers keep striking with the chemical fumigant methyl
bromide, but the nematodes keep coming back. Now farmers face a ban on methyl
bromide by the year 2001. This means their main weapon may be taken away and
what alternatives will they have for continuing this ongoing struggle?
Fortunately for pepper farmers, they have an unswerving ally in Richard L.
Fery. This geneticist with USDA's Agricultural Research
Service in Charleston, South Carolina, has developed bell peppers that have
genetic resistance to the southern root-knot nematode, Meloidogyne
Fery and his research colleagues, who began the bell pepper project at the
agency's U.S. Vegetable Laboratory in 1981, have released two resistant
varieties, Charleston Belle and Carolina Wonder.
"These are the first commercial nematode-resistant bell peppers, and we
think they will be a big help to growers," says Fery.
In 3 years of field and greenhouse tests, Fery showed that both the
Charleston Belle and Carolina Wonder are highly resistant to the nematodes. The
reason, he says, is a single dominant gene called the N gene, which
gives the plant the ability to ward off nematodes that would otherwise infest
the roots and eventually weaken or kill the plant.
Considering the ban scheduled on methyl bromide to protect the atmospheric
ozone layer, growers welcome this genetic resistance. It could be a key
component of an integrated pest management strategy relying on natural pest
control methods to reduce dependence on chemicals.
Technician Melissa Hulsey counts southern root-knot nematode eggs extracted
from an infected pepper root.
"Anything that is resistant to insects would be beneficial," says
Emilo Davis of the new peppers. He is with Gro-South of Alabama, Inc., in
Montgomery. Though Davis does not have severe nematode infestations in his
fields, he uses chemicals to control other pests.
The southern root-knot nematode, a microscopic worm that likes sandy,
well-drained soil, does its damage by entering a plant's roots and feeding on
them. As the nematodes feed, they start to swell, changing from eel-shaped to
pear-shaped. They remain in the roots until they die.
Continued feeding by the nematodes eventually begins to reduce the host
plant's ability to take in water and nutrients, making it more susceptible to
damage from heat and nutritional deficiencies. Once the soil has been infested
with the nematodes, it remains infested.
Injecting methyl bromide into the soil 2 to 4 weeks before planting seeds is
the most effective way to control nematodes, says David Nagel, a horticulturist
at Mississippi State University. Each year, pepper crops account for 12 percent
of the methyl bromide used in the United States for soil fumigation.
"Without an alternative, this could become a serious problem,"
says John VanSickle, professor of Food and Resource Economics at the University
Susceptible pepper plant roots with extensive galling [thickened, lumpy
portions] are heavily infested by the southern root-knot nematode.
In a 1995 economic study, VanSickle and other researchers calculated the
economic costs to the bell pepper industry that would result from a methyl
bromide ban. VanSickle's study was aimed at Florida's winter growing season
from November through June. It projected that in Florida, losses in sales alone
would be $79 million. The total economic loss would be about $127 million,
resulting in a loss of about 1,567 full-time jobs.
The VanSickle study estimated the loss of methyl bromide for all farming
would cost about $1.045 billion and 13,345 full-time jobs.
The new nematode-resistant peppers could help minimize the losses that will
result from a methyl bromide ban.
"Although the peppers and seeds could cost more at the retail
level," says Kenneth Jackson of the Degiorgi Seed Company, "the
benefits will outweigh the cost."
Both Charleston Belle and Carolina Wonder are dark green when harvested, and
they mature to bright-red color. The fruits are sweet, and they look and taste
like bell peppers currently in the market. The new peppers, both of the species
Capsicum annuum, take from 63 to 70 days to ripen.
Charleston Belle and Carolina Wonder seeds have been offered to about 250
wholesale and retail seed companies for sale to the general public beginning in
1998, says Fery. By Pat Sanchez.