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Weed Hosts of Bean Thrips

Below are some favored weed hosts of bean thrips and some stages of their development you might see during fall. The winter annual species may be present as seedlings after fall rains arrive and where irrigated. In fall, the perennial hosts will typically be mature plants and may be flowering. Note that although late summer to early winter are critical bean thrips monitoring and management times, better times to monitor and control weeds may occur earlier in the growing season.

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Annual broadleaves
  • Annual sowthistle
  • Little mallow (cheeseweed)
  • Whitestem filaree
  • Prickly lettuce
  • Russian thistle
  • Bermudagrass
  • Dallisgrass
  • Johnsongrass
  • Tree tobacco

Names link to more information on identification and biology.

Click on photos to enlarge
Annual broadleaves
Sowthistle seedling
Annual sowthistle seedling
(Sonchus oleraceus): Sunflower family; summer or winter annual; seed leaves markedly stalked, almost spoon-shaped, rounded at tip and often have grayish powdery bloom; injured tissue bleeds milky white latex.
Little mallow, Malva 
				parviflora, seedling.
Little mallow (Cheeseweed) seedling
(Malva parviflora): Mallow family; winter annual; seed leaves heart shaped, sometimes with red tinge; true leaves roundish with wavy, shallow-toothed margins.
				filaree seedling.
Whitestem filaree
(Erodium moschatum): Geranium family; winter annual or biennial; seed leaves 3- to 4-lobed, center lobe largest; true leaves arranged as opposite or alternate; leaves and stems bristly and hairy.
Seedling of 
				prickly lettuce, Lactuca serriola.
Prickly lettuce seedling
(Lactuca serriola): Sunflower family; winter annual or biennial; seed leaves about 2 times longer than wide; first true leaves with rounded margins; injured tissue bleeds milky white latex.
Seedling of  				prickly lettuce, Lactuca serriola.
Prickly lettuce mature plant
Mature plant grows erect and bears numerous creamy yellow flowers on branches off the main stems; leaves are alternate, clasp the stem, and may be lobed or entire with prickly margins.

Russian thistle mature plant
Russian thistle mature plant
(Salsola tragus): Goosefoot family; summer annual; mature plants are spherical bushes up to several feet tall. After they turn grayish brown, the plants break away from the roots at the soil line.

Bermudagrass mature plants
(Cynodon dactylon): Grass family; perennial that becomes dormant during cool weather; mature plant forms dense mats with spreading and branching stolons that root at the nodes; flowering spikes radiate from a single point at the tip of the stem.
Dalllisgrass flower head
Dallisgrass flower head
(Paspalum dilatatum): Grass family; perennial; flower head consists of 3 to 6 spikes that arise apart on the stem and often droop.
Dallisgrass mature plants
Dallisgrass mature plants
Mature plants form loose bunches, 1 to 4 feet (0.3–1.2 m) high, or low and spreading; leaf sheath somewhat flattened.

Johnsongrass rhizomes.
(Sorghum halepense): Grass family; perennial; persists and spreads via underground stems (rhizomes), which are thick, fleshy, and segmented; roots and shoots can rise from each rhizome segment; leaves have a prominent whitish midvein.

Johnsongrass (foreground)
Mature plant grows in spreading, leafy patches that may be as tall as 6 to 7 feet (1.8–2.1 m). Most any grass can host bean thrips, including crop grains such as wheat (shown in the background).

Free tobacco
Tree tobacco
(Nicotiana glauca): Nightshade family; perennial broadleaf; grows to become a small tree; foliage has strong, unpleasant scent; plant highly toxic if ingested; yellow tubular-shaped flowers spring through fall.

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