Wild mustard is the field weed turned garden volunteer. It colonises disturbed ground in early spring, flowers yellow a few weeks later, and sets seed before most gardeners have noticed it. The flowers look like cultivated mustard, but the plant is looser and more branching, 18 to 48 inches tall.
It is not sown deliberately; it arrives on its own in vegetable beds and field edges, usually from seed that has sat in the soil for years waiting to be turned up. Each plant drops thousands of seeds, so the job is to pull it before the pods form, which is easy when the soil is damp and the plant is young. The young leaves and flower buds are edible with the usual mustard bite.
Mustards are allelopathic, which means they release compounds that slow the germination and growth of plants around them, so a patch left to stand in a seed bed costs you more than the space it takes. It is also a host for the same pests as the brassica crops, cabbage white caterpillars and flea beetles among them, which is another reason to keep it out of a kitchen garden.
Aphids
Aphididae →Clusters of small soft insects on new growth and flower buds.
Knock off with a strong jet of water. Ladybirds and lacewings are natural predators. Insecticidal soap as last resort.
Flea Beetle
Alticini →Small round shot-holes scattered across leaves; tiny dark beetles that jump when disturbed. Heavy feeding stunts young plants.
Use floating row covers on seedlings. Remove crop debris and weeds that harbor beetles. Apply kaolin clay or spinosad if damage is severe.