72 PLANT QUARANTINE AND CONTROL ADMINISTRATION [April-June, 
be easily injured. Several hundred species of deciduous, herbaceous, and ever- 
green nursery plants have been treated under as varied conditions as possible, 
to determine the safest methods for disinfecting each species. It has been found 
that insecticidal treatments may be applied safely to the roots of nursery plants 
only when the plants are dormant or semidormant. If they are growing vigor- 
ously, serious injury may result. Normal, well-nourished plants usually with- 
stand treatment when weak, poorly developed plants may be killed. 
A. Potted greenhouse plants 
There is no safe and effective method at the present time for destroying beetle 
infestation in the soil of potted plants. The infestation may be removed from 
Eome plants by washing all soil from the roots and repotting in disinfected soil, 
but this is not recommended for general practice. 
The nurseryman who desires to ship potted plants should take every precau- 
tion to have both soil and plants free of infestation at the time of potting. 
After potting, the plants should be grown in properly protected frames or houses 
to prevent infestation. 
B. Hardy herbaceous plants 
Many hardy herbaceous plants may be disinfected in commercial nurseries 
while in storage during the dormant season. These plants may be divided into 
three groups, according to the method by which they should be treated. 
Washing the roots. — Infestations can be removed safely from some species 
only by washing all the soil from their roots. Among these species are the 
following : 
Aconitum californicum Monkshood. 
Aconitum fischeri Azure monkshood. 
Arenaria balearica Corsican sandwort. 
Arenaria montana Mountain sandwort. 
Aubrietia deltoidea Common aubrietia, 
Artemisia abrotanum Southernwood. 
Artemisia vulgaris (lactiflora) White mugwort. 
Bellis perennis _. English daisy. 
Boltonia asteroides _ White boltonia. 
Calimeris incisa C alimeris. 
Campanula per ski folia.- Peachleaf bellflower. 
Centaurea dealbata Persian centaurea. 
Centaurea macrocephala Globe centaurea. 
Centaurea montana Mountain-bluet. 
Centranthus ruber (Valeriana coccinea; V. rubra) Jupitersbeard. 
Chelone glabra White turtlehead. 
Chelone lyoni Pink turtlehead. 
Chrysanthemum sp._ Chrysanthemum. 
Delphinium sp Larkspur. 
Digitalis lanata Grecian foxglove. 
Digitalis purpurea Common foxglove. 
Erigeron coulteri.. Fleabane. 
Festuca glauca Blue fescue. 
Oaillardia aristata (grandiflora) Common perrennial gaillardia. 
Oypsophila paniculata B aby sbreath . 
Oypsophila repens Creeping gy psophila. 
Hibiscus moscheutos Common rosemallow. 
Hypericum calycinum St. Tohnswort. 
Hypericum moserianum .. Goldflowcr. 
Ligularia clivorum (Senecio clivorum) Giant groundsel. 
Malva moschata Musk mallow. 
Monarda didyma Oswego beebalm. 
Senecio pulcher Uruguay groundsel. 
Sidalcea Candida.. - White prairiemallow. 
Silene schafta Schafta catchfly. 
Stachys grandiflora Big betony. 
Stachys lanata Woolly betony. 
Statice armeria (Armeria cephalotes)... Common thrift. 
Statice armeria (Armeria maritima) Common thrift. 
Valeriana officinalis Common valerian. 
Washing the roots or hot-water treatment. — Some species of herbaceous plants 
can be treated successfully both by washing the soil from the roots and by 
submerging, while in a dormant state, in hot water. The species marked with 
an asterisk can be subjected to the hot-water treatment without danger of 
injury ; the others are less resistant, but may be treated if sufficient care is 
exercised. 
