How Can I Control Dodder?

Do you want to try controlling dodder with cultural control methods?

Do you want to prevent a dodder infestation using cultural methods?

Do you want to control dodder seedlings?

Do you want to prevent a dodder infestation?

Do you want to try controlling dodder with biological control method?

Do you want to try controlling dodder by planting dodder-resistant varieties?

Planting nonhost plants can be an effective means of managing a dodder infestation. Plants that aren’t hosts of dodder include grasses and many other monocots including lilies. Plants that grow primarily during winters such as crucifers and legumes and transplanted trees and shrubs usually are good alternatives. Dodder can’t penetrate tree bark, but it can penetrate tree foliage if it can contact it. Be sure to remove weeds in these plantings, so the weeds don’t serve as hosts for dodder and increase the amount of dodder seed in the soil.

If you see dodder seedlings before they attach to a host, remove them by cultivation or hand pulling. If you see dodder soon after it has attached itself to a host, prune the infected portion of the host plant 1/8 to 1/4 inch below the point of attachment, otherwise, the dodder can regenerate from the haustoria left embedded in the host plant. If you allow freshly removed dodder to contact a healthy host plant, a new connection sometimes occurs. If the dodder plants have set seeds, remove the plants from the area to prevent future infestations. Place plants in a plastic bag, and dispose of them in the trash.

Burning reduces a dodder infestation as long as you destroy the invaded tissue of host plants along with the dodder to prevent regeneration from embedded haustoria. Burning kills only some of the dodder seed; the amount of seed destroyed depends on the duration and intensity of the fire.

The use of dodder-free planting seed has long been a primary way of preventing the spread of dodder infestations. Clean and inspect clothing and equipment before moving from infested to non-infested areas. Once you know an area is infested, you must manage it to prevent the further production of dodder seed. Isolate small infestations, and remove them by hand before the plant produces seed. Monitor larger infestations, and mow, prune, burn, or spray herbicides to prevent seed production.

Several disease organisms are known to infect dodder including Fusarium tricinctum and Alternaria species, which attack swamp dodder (C. gronovii), and A. alternata and Geotrichum candidum, which attack field dodder (C. pentagona). Researchers in China have found that a suspension of Colletotrichum gloeosporioides can selectively control the dodder species C. chinensis and C. australis in soybeans. Difficulty in culturing and applying these organisms has limited their commercialized use.

Breeding programs aimed at developing dodder-resistant varieties are not known to exist. However, some varieties of normally susceptible species have some resistance. Several varieties of processing tomatoes, a plant generally susceptible to dodder, have been observed to be either resistant or tolerant to dodder attack.

Usually dodder can’t be eliminated with a single treatment or in a single year. If you see native dodders infesting herbaceous landscape and garden plants, take immediate action to eliminate or reduce the infestation. Effective management requires control of the current population, prevention of dodder seed production, and suppression of new seedlings in subsequent years. Where extensive infestations exist, remove the infested host plants and replant with nonhosts. In vegetable gardens rotate to nonhost crops for several years. When you plant a host crop again, remove any new dodder plants as soon as possible.