Q. When my lettuce plants began wilting a few weeks ago, even though the weather was cool and the soil moist, I pulled some up to find masses of insects on the roots. What are they? The lettuces are in pots, in re-used soil.
A. They are most likely lettuce root aphids. A few of my lettuces were afflicted with them only once. A sign of their presence is wilting, even in cool conditions, and the heads fail to develop properly.
These aphids gather in clustered colonies on the roots and are covered with a white powdery wax. A mass of whitish, woolly matter can be present along with the aphids. Winged adults develop that can spread from place to place. They overwinter in the egg stage.
Get rid of the lettuces and the soil . Use only fresh planting mix next year. In the open garden, dig the soil deeply and allow it to dry out well before planting lettuce. Keep moving the planting site for each batch of transplants or seeds.
My one experience with root aphids on lettuce was never repeated. Infestations are not common in home gardens.
Q. A California tree poppy (Romneya) that has been in the garden for around six years started roaming this year. Two small plants appeared several metres from the parent plant. Is this an oddity or a characteristic of the plant?
A. These shrubby Californian perennials (Matilija poppy, Romney coulteri) are loved for their large, crinkly-petaled, poppy-like flowers with fluffy golden centres. Once well established in a garden, they can become fairly aggressive spreaders via underground rhizomes.
My plant has done this, popping up on the opposite side of a wide pathway and in places even farther away. I once heard from a gardener whose Romneya managed to travel underneath a garage to produce a new plant by the far wall. So far, I’ve not found it a problem to remove offshoot plants where they are not wanted.
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