WSU Extension

Hortsense

Weeds
 
Annual bluegrass 
Barnyardgrass 
Bentgrass, creeping 
Bermudagrass 
Bittercress (Shotweed, Hairy bittercress) 
Bittersweet nightshade (European bittersweet) 
Black medic 
Blackberry (Himalayan, Evergreen, Pacific) 
Blue mustard (Purple mustard, Tenella mustard) 
Brackenfern, western 
Buffalobur 
Bull thistle 
Buttercup, creeping 
Canada thistle 
Catchweed bedstraw (Cleavers) 
Catsear, common (False dandelion) 
Chickweed, common and mouseear 
Clover 
Comfrey 
Crabgrass 
Dandelion 
Dock (Curly, Broadleaf) 
Dodder 
Downy brome (Cheatgrass, Downy chess) 
Dwarf mistletoes 
English daisy (Lawn daisy) 
English ivy 
Field bindweed (Wild morningglory) 
Field pennycress (Fanweed) 
Flixweed 
Foxtail (Green, Yellow, Bristly) 
Garden loosestrife 
Giant hogweed 
Goldenrods 
Groundsel, common 
Hawkweeds 
Hedge bindweed 
Henbit 
Herb Robert (Robert geranium, stinky Bob) 
Horsetails (Scouringrush) 
Horseweed (Marestail) 
Knapweeds 
Knotweeds (Bohemian, Giant, Japanese, Himalayan) 
Kochia 
Lambsquarters, common 
Liverworts 
Mallow, common (Cheeseweed, Buttonweed) 
Nightshades 
Oxalis (Creeping woodsorrel) 
Parrotfeather and Eurasian watermilfoil 
Pineappleweed 
Plantain (Broadleaf, Buckhorn) 
Poison hemlock 
Poison ivy and Poison oak 
Prickly lettuce (China lettuce) 
Prostrate knotweed 
Puncturevine (Tackweed, Goathead) 
Purple deadnettle (Red deadnettle) 
Purple loosestrife (Purple lythrum) 
Purslane, common 
Quackgrass 
Red sorrel (Sheep sorrel) 
Redroot pigweed (Rough pigweed) 
Redstem filaree (Stork's bill, Crane's bill) 
Reed canarygrass 
Russian thistle (Tumbleweed) 
Ryegrass, annual (Italian ryegrass) 
Salsify (Goatsbeard) 
Scotch broom 
Shepherd's-purse 
Smartweeds 
Sowthistle, annual and perennial 
Speedwells 
Spurges (Prostrate spurges) 
St. Johnswort, common (Goatweed, Klamathweed) 
Stinging nettle 
Tansy ragwort 
Tumblemustard (Jim Hill mustard) 
Velvetgrass (Common velvetgrass) 
Velvetleaf 
Water primrose 
Waterhemlock, western 
Yellow nutsedge 



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Caption: Dwarf mistletoe
Photo by: R.S. Byther
  
Weeds : Dwarf mistletoes : Arceuthobium spp.
(revision date: 6/9/2014)

Family: Loranthaceae
Cycle: Perennial
Plant Type: Parasitic

Biology
Dwarf mistletoe is a parasitic plant that grows on the branches or occasionally on the trunk of a host tree. Mistletoe shoots range in color from yellowish to olive-green to reddish depending on species. Shoot size is also variable, ranging from 1/4 inch to 8 inches long. The host tree's branches become swollen and spindle-shaped at the infection site, and may develop witches' brooms (loose fans to tight clumps of small twigs and foliage). Severe infestations can greatly reduce growth of the tree, sometimes causing dieback or death. However, since dwarf mistletoe survival depends on the survival of the host plant, death of entire trees is uncommon. Dwarf mistletoe spreads by sticky seeds that are shot forcibly away from the parent plant. In parts of Oregon, true or leafy mistletoes (Phoradendron spp.) also occur. Host plant symptoms and mistletoe appearance are somewhat similar to dwarf mistletoes; however, some true mistletoes have oval leaves 1 to 1 1/2 inches long. Seeds of true mistletoes are not forcibly ejected, but are typically spread by birds feeding on the berries.
Habitat
Dwarf mistletoe hosts include conifers such as Douglas-fir, true firs, larch, hemlock, pines, and junipers. In Oregon, true mistletoes may be found on junipers, firs, and hardwoods such as oaks and maples. Most mistletoes are fairly host-specific and will not infect species other than their host plant or its close relatives.

Management Options

Non-Chemical Management
  • Remove mistletoe from host tree by pruning out witches' brooms or hand-picking the parasite.
  • Plant non-host species in areas where mistletoe is a problem.
Select non-chemical management options as your first choice!

Chemical Management

No chemical controls are recommended for homeowner use.

Images

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Caption: Dwarf mistletoe
Photo by: R.S. Byther