Tagetes minuta

[MikeH]

Anyone growing this? Apparently secretions from its roots are effective against pathogenic nematodes and, more interestingly to me, have a herbicidal effect, inhibiting the growth of certain plants growing nearby. It has been found effective against perennial weeds such as Ranunculus ficaria (Celandine), Aegopodium podagraria Ground elder), Glechoma hederacea (Ground ivy), Agropyron repens (Couch grass) and Convolvulus arvensis (Field bindweed).

What got my attention is Agropyron repens which is called quackgrass or twitchgrass in my area. Every little severed piece of root produces a new plant. In the early days of our raised beds when we were trying to improve the subsoil (our topsoil was scraped off for landscaping), we dug down with a digging fork to loosen the soil up and mix compost in. Often we'd come across rhizomes a foot or more down. At first I thought they were dead. Sad experience taught me they weren't. While we don't disturb the soil much anymore, I'm still interested in ways of dealing with the weed. Herbicides are not an option.

[Hristo]

I grew it 5 years ago and it self sows after that. It's daylength sensitive and easily reaches 2+ m. hight. The field bindweed is my worst weed and it happily climbs on the tagetes. That's all I can tell.

[12540dumont]

Bindweed....the nemesis. Leo spends hours digging it with a garden fork.
field bindweed is a hardy perennial found throughout California below the 5,000-foot elevation line. It spreads from an extensive rootstock and from seed. Most parts of the bindweed roots and rhizomes can produce buds that can create new roots and shoots. Roots capable of budding are found to depths of 14 feet. Fragments of vertical roots and rhizomes as short as 2 inches can form new plants. Lateral roots serve another important function. About 15 to 30 inches from the parent plant, a lateral often turns downward, becoming a secondary vertical root, and sends out both roots and shoots from the turning point. By this means a single field bindweed plant can spread radially more than 10 feet in a growing season. This extensive underground network allows for overwintering without foliage, and it can persist for many years in the soil.

One to four dark brown seeds (Figure 8) are produced in round, smooth, 1⁄4-inch capsules. An average plant produces about 550 seeds. Within one month after forming, the seed coat matures and becomes impervious to water. Seed that is 60 years old has been found to be viable. Once the seed coat is weakened, the seed will germinate at temperatures of 41° to 104°F.

Drought tolerance is a characteristic of field bindweed. In California, it seems to prefer heavy clay soils rather than sandy soils. When water is withheld, bindweed competes better than most other plants. If an area is well watered, some ornamentals might compete better than the bindweed; however, in most cases, bindweed will flourish and twine up plants. In the landscape, field bindweed will survive with sprinkler or drip irrigation. If there is no summer water, the plant reduces its seed production first and then reduces growth and leaf size, but it still will produce some flowers and seed.

I just keep hoeing the tops off.

The only thing that I have heard that eliminates them is covering the soil with black plastic (with no holes) and leaving it there for 3-5 years.

No light = no bindweed. However, I can't farm if it's all covered with black plastic.

Sigh.

[Hristo]

The alfalfa can clean the bindweed plants in 2 years, but of course will not clean the seeds. Very few plants can compete with (young) alfalfa.