With only a few weeks remaining before garlic harvest, weed control remains a main focus. Weeds are bound to occur on a healthy, organic farm. Our goal is not to prevent weeds by repeated use of weed killing herbicides, but instead we control the weed pressure to a tolerable level.
Organic weed control methods are:
- cover crops
- crop rotations
- hand pulling
Intolerable (very time-consuming/impacting garlic growth) weed pressures develop when three conditions or a “weed triangle” occurs:
- A susceptible crop. Garlic is a weak competitor and does not thrive in weedy fields.
- A large weed seed bank in the soil.
- A favorable environment for weed growth.
Our goal is to reduce weed seed populations while maintaining an unfavorable environment for weed growth using organic weed control methods. Field observation is the key to making appropriate crop cultivation decisions for managing weeds organically. Identifing weeds gives us information to plan and improve our tillage, cover cropping, soil fertility and rotation strategies:
|Blackseed Plantain: Plantago rugelii||Perennial from a basal rosette with broad oval leaves. Often mistaken for the closely related broadleaf plantain (Plantago major). Found throughout the United States, primarily a weed of turfgrass.|
|Common Burdock: Arctium minus||A biennial that produces a rosette of very large leaves in the first year and a branched stem with many burs during the second year. Found across the upper half of the United States and is most commonly found as a weed of pastures, hay fields, and fence rows|
|Common Milkweed: Asclepias syriaca||Perennial, erect, from a deep rhizome that excretes a milky sap when broken. Found throughout the northeastern United States, south to Virginia and northern Georgia, and west to the Rocky Mountains|
|Common Purslane: Portulaca oleracea||Prostrate, fleshy, succulent summer annual that is able to tolerate poor, compacted soils and drought. Common purslane is a common weed of gardens, horticultural and agronomic crops and is found throughout the United States.|
|Common Ragweed: Ambrosia artemisiifolia||Summer annual, 0.2-2.5 m tall, found throughout the United States, producing abundant pollen that is a primary cause of hay fever.|
|Curly Dock: Rumex crispus||Taprooted perennial, developing a basal rosette of wavy-margined leaves and an unbranched stem that may reach 5 feet in height. Found throughout the United States primarily as a weed of pastures, hay fields, forages, landscapes, and some agronomic crops.|
|Dandelion: Taraxacum officinale||A perennial from a basal rosette with yellow flowers and a ‘puff-ball’ seedhead. Dandelion is one of the most common and problematic weeds of turfgrass and lawns throughout the United States. Dandelion also occurs as a weed of container ornamentals, landscapes, nurseries, orchards, and occasionally agronomic crops.|
|Goosefoot: Chenopodium alba||There are about 100 species in the genus, which grows in temperate regions around the world. They are weedy, rank-smelling plants. Some of the species in the genus have leaves that resemble the foot of a goose.|
|Pennsylvania Smartweed: Polygonum pensylvanicum||A summer annual weed of horticultural, agronomic, and nursery crops that may reach 3 1/2 feet in height. Pennsylvania smartweed is distributed throughout the United States|
|Quackgrass: Elytrigia repens||A perennial grass weed from rhizomes that may reach 3 1/2 feet in height. Quackgrass is a common weed of agronomic crops, turfgrass, lawns, nurseries, and landscapes that may be found in the northern United States.|
|Redroot Pigweed: Amaranthus retroflexus||An erect summer annual that may reach 6 1/2 feet in height. Redroot pigweed is an abundant seed producer that may be found throughout the United States in horticultural, nursery, and agronomic crops, landscapes, roadsides, and also in pastures and forages.|
|Shepherd’s-purse: Capsella bursa-pastoris||Plants grow from a rosette of lobed leaves at the base. From the base emerges a stem about 0.2 to 0.5 meters tall, which bears a few pointed leaves which partly grasp the stem. The flowers are white and small, in loose racemes, and produce seed pods which are heart-shaped.|
|Smooth Crabgrass: Digitaria ischaemum||Summer annual, having a prostrate or ascending growth habit, with leaves and sheaths that do not have hairs and stems that do not root at the nodes. Found throughout the United States.|
|Spiny Sowthistle: Sonchus asper||An annual that may reach as much as 6 feet in height with bluish-green leaves and stems that emit a milky sap when cut. Spiny sowthistle is primarily a weed of landscapes, winter small grains, pastures, hay fields, orchards, and roadsides. It is found throughout the United States.|
|Tall Morningglory: Ipomoea purpurea||A trailing or climbing annual vine with heart-shaped leaves and purple to white flowers. Primarily a weed of agronomic crops, nurseries, landscapes and noncrop areas that is found throughout the eastern half of the United States except for the far northern states.|
|Wild Carrot or Queen Anne’s Lace: Daucus carota||A biennial that closely resembles a typical garden carrot during the first year of growth. During the second year of growth, the plants produce stalks with white, flat-topped flowers. Found throughout the United States.|
Weed identification source: Virginia Tech Weed Identification Guide