Pest of the Week - Garlic Mustard

Garlic Mustard (Alliaria petiolata) is a biennial herb in the mustard family Brassicaceae.  Garlic mustard is invasive plant native to Europe.

Garlic mustard is easily distinguished from all other woodland mustard plants by its characteristic odor of garlic and the tall flower stalks covered with numerous small white flowers in May.  The alternate, coarsely toothed, broadly triangular stem leaves with a distinct petiole are also characteristic. The garlic odor gradually dissipates by autumn, and garlic mustard rosettes may then be mistaken for violets (Viola spp.) or immature white avens (Geum canadense).

For centuries Europeans have used garlic mustard for a great variety of dietary and medicinal purposes. It is rich in vitamins A and C and makes a spicy addition to salads or cooked dishes.  It is thought that the plant was introduced to the United States by immigrants in the 1860s and was first recorded in Long Island, New York.

An average garlic mustard plant will produce 22 siliques, each of which can contain as many as 28 seeds. Studies have shown that a particularly vigorous plant may produce as many as 7,900 seeds although the average is more likely to be in the 600 seed range. The seeds generally germinate within one to two years, but may remain viable for up to five years in the seed bank. Seed dispersal is mainly by humans or wildlife carrying the seeds.

Garlic mustard exudes antifungal chemicals into the soil that disrupt associations between mycorrhizal fungi and native plants, suppressing native plant growth.  Because of this. garlic mustard has aggressively invaded numerous forested natural areas and is capable of dominating the ground layer. It is a severe threat to many natural areas where it occurs because of its ability to grow to the exclusion of other herbaceous species.

Garlic mustard flower
André Künzelmann/UFZ

Garlic mustard seedlings
DePauw University

Garlic Mustard Seed - Chris Evans

Here is a link to a short video covering all aspects of this plant in greater detail Garlic Mustard video

Because this plant is so difficult to eradicate once it is established, familiarize yourself with the flower, the plant and the habitat where it grows to find infestations early. Monitor sites regularly to remove plants prior to seed set. 

Additional Information

Garlic Mustard Video

Herbaceous Forbs - Garlic Mustard - Plant Conservation Alliance

Invasive species harms hardwoods by killing soil fungus - Harvard University

Zuwanderer unterdrücken das Wachsen einheimischer Baumarten - Helmholtz-Zentrum für Umweltforschung - UFZ

Garlic Mustard - New York Invasive Species Information

Pest of the Week - Pokeweed

Pokeweed (Phytolacca americana) is a native of North America and has become established in Europe. In North America, it is most common in the eastern United States and southeastern Canada. It grows as far west as Texas but is rare in the Great Lakes region. Its range extends north into Ontario and south as far as Mexico.

The scientific name for pokeweed is derived from phytos, the Latin word for plant, and lacca, which refers to the deep reddish purple of the berries. The most frequently used species name, americana, refers to its native land. The less common species name, decandra, means "having ten stamens." The common name poke is a contraction of puccoon or pocan, which the Algonquin Indians of Delaware called the familiar wild plant.

A native perennial plant that can grow up to 10' tall, branching regularly like a small tree. The stems are smooth, round, and hairless, varying from light green to brilliant purplish red. The leaves are alternate on the stem, simple, entire, with long leafstalks. Flowers are borne in elongated clusters called racemes. The pronounced clusters of berries are green when immature and ripen to a dark purple or black. Reproduction is by seeds.

Pokeweed Berries
Staff CDFA, California Department of Food & Agriculture, Botany Laboratory

Pokeweed Flowers
Brandeis University

Solitary Pokeweed Leaf
Auburn University

Because of the danger of human poisoning, pokeweed should be removed when discovered. This is especially true if the plants are in hedges, gardens, and other areas adjacent where children may be attracted by clusters of berries.

Additional Information

Forage ID Library - University of Arkansas - Cooperative Extension

Poisonous Weeds in Horse Pastures - Rutgers Univeristy - NJAES

Pokeweed - Penn State University - PennState Extension

USDA - Natural Resources Conservation Service

IPM Notes from October 2, 2014

Several weeks ago it was incorrectly stated that winter rye was growing where the sweet corn was growing. Oats are the correct cover crop that is currently growing there. The oat plants have some rust and cereal leaf beetle damage, and they will not survive the winter, unlike winter rye.

The field corn has a current moisture content of 23%. To harvest the corn the moisture level needs to be around 14%. Hopefully the corn will be harvested within the next week.

The popcorn has a current moisture content of 26.5%. Like the field corn the moisture level needs to be around 14%. As mentioned several weeks earlier the non-BT popcorn is showing plenty of corn borer damage. Some of the stalks have blown over due to the weakened stalks. The issue becomes can the popcorn dry down soon enough in order to be harvested, before incurring more damage.

The soybean show some stink bug damage, but should be ok to harvest in the near future.

In the demonstration plots the Spanish peanut crop had some foliar leaf disease and also peanut damage from voles. They are not yet ready for harvesting. The pepper plants rebounded nicely and have produced a nice crop the last couple of weeks. Also within the pepper plot the garden-in-a-bag plants have performed well this year. The ever-bearing strawberries are still producing fruit, and the June bearing plants look large and healthy. The sorghum plants have also done well this year.

There are no summaries for the insect traps. They have been taken down for the season.