Problem Weed in Strawberries: Dwarf Snapdragon

Dwarf snapdragon is a weed that occurs in all parts of Ontario, usually on roadsides and waste areas, but it has become a major problem in strawberry fields and some orchards.

Like all weeds, Dwarf Snapdragon has other names. Scientifically it is known as Chaenorrhinum minus. It is also called dwarf toadflax, small toadflax, or the Railroad weed, since it thrives on the gravelly and cinder area of railroad beds. A member of the Figwort (Snapdragon) family, it looks similar to toadflax, but dwarf snapdragon is smaller (about 8" tall), with shorter leaves and finer brittle stems that break easily. The light blue to purplish flowers (compared to yellow toadflax flowers) stay in bloom for only 24 hours. Dwarf snapdragon has a short taproot, while the perennial toadflax grows from thick underground creeping roots. The leaves are often hairy and almost sticky.

Dwarf snapdragon is an annual that spreads by seed only. It flowers from June to September. Under dry conditions, it will have 2 peaks in flowering, before and after the rains. Since it grows from seed to flower in about 45 days, it produces large numbers of seeds.

Controlling dwarf snapdragon in strawberries is a challenge, and is based on prevention. If you plant in a field where dwarf snapdragon has seeded, be ready to cultivate out young seedlings as they emerge. Dacthal will control new seedlings, but needs to be applied before weeds emerge in the spring, at renovation, near Labour Day and again before mulching. Sinbar does not control dwarf snapdragon, but regular use will suppress it.

Field edges should be scouted frequently. Mowing is not the answer with this weed, because mowed plants will quickly grow new shoots from the base, and often still flower and seed after mowing!

Dwarf snapdragon can be very competitive with strawberries, and some growers have abandoned fields a year or two early due to this weed. So learn what it looks like and be vigilant about removing it from new plantings.

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