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TranslateCentaurea diffusa, (diffuse knapweed)
Centaurea diffusa (diffuse knapweed)
Also known as “White knapweed” or “Tumble knapweed”.
Family: Asteraceae. Genus: Centaurea. (are found only north of the equator, mostly in the Eastern Hemisphere).
Can be an annual or biennial plant.
Height from 10 to 60cm, Flowers: June to September. (Alicante, Spain).
This plant is native to eastern Mediterranean, Austria, Hungary, Greece and Romania being the primary countries of its origin.;
Centaurea diffusa prefers light, dry porous soils, sandy type soils are ideal, this type of soil gives good drainage and air to the root system, as the plants roots do not like heavy soils that contain water. Here in Spain we have large areas of sandy soils especially near the coast.
Diffuse knapweed (like many species of knapweed) is an important pollen source for most species of bees, particularly honey bees, in mid to late summer. Unfortunately, it is not welcome in agriculture and is poisonous to many types of livestock that are grazing in fields. It is not an easy “weed” (A Plant is named a weed when growing in the wrong place), too eliminate as it has a large taproot and a single plant can produce up to 18000 seeds, which are easily dispersed in the wind. Centaurea diffusa is a serious invading species in parts of western North America, proving to be very hard to eradicate in unwanted places. Knapweed plants are harmful because they are strongly allelopathic, the root system produces powerful toxins that stunts the growth of many types of plants, including grasses, growing around them.
Biological means, by the way of insects have been introduced to North America to help to control many types of knapweed. These insects were introduced from the Eastern Mediterranean countries where the plants originated from. The Lesser knapweed flower weevil Larinus minutus) lay their eggs on the seed heads of the plant. knapweed root weevil (Cyphocleonus achates) lay their eggs at the root of the plant for the larvae to feed on. The Yellow-winged knapweed root moth (Agapeta zoegana) and two species of Tephritidae flies (Urophoraaffinis and Urophora quadrifasciata) all help to contain Centaurea diffusa and also another invasive knapweed plant “Spotted knapweed”.
Physical control to remove knapweed is an effective way of controlling knapweed, although this is very labour intensive, as it involves digging up the long taproot to be effective. (Obviously this has to be done before the seed heads develop, otherwise you will be aiding the plant to disperse its seeds). Burning and cutting down knapweed is not always successful, because if the taproot survives, then the plant has a very good chance to recover.
Chemicals used in spraying knapweed can have a short-term control advantage, but some plants have shown to build up a resistance to this and in the long term these plants could prove to be harder to eradicate.
Read MoreAlso known as “White knapweed” or “Tumble knapweed”.
Family: Asteraceae. Genus: Centaurea. (are found only north of the equator, mostly in the Eastern Hemisphere).
Can be an annual or biennial plant.
Height from 10 to 60cm, Flowers: June to September. (Alicante, Spain).
This plant is native to eastern Mediterranean, Austria, Hungary, Greece and Romania being the primary countries of its origin.;
Centaurea diffusa prefers light, dry porous soils, sandy type soils are ideal, this type of soil gives good drainage and air to the root system, as the plants roots do not like heavy soils that contain water. Here in Spain we have large areas of sandy soils especially near the coast.
Diffuse knapweed (like many species of knapweed) is an important pollen source for most species of bees, particularly honey bees, in mid to late summer. Unfortunately, it is not welcome in agriculture and is poisonous to many types of livestock that are grazing in fields. It is not an easy “weed” (A Plant is named a weed when growing in the wrong place), too eliminate as it has a large taproot and a single plant can produce up to 18000 seeds, which are easily dispersed in the wind. Centaurea diffusa is a serious invading species in parts of western North America, proving to be very hard to eradicate in unwanted places. Knapweed plants are harmful because they are strongly allelopathic, the root system produces powerful toxins that stunts the growth of many types of plants, including grasses, growing around them.
Biological means, by the way of insects have been introduced to North America to help to control many types of knapweed. These insects were introduced from the Eastern Mediterranean countries where the plants originated from. The Lesser knapweed flower weevil Larinus minutus) lay their eggs on the seed heads of the plant. knapweed root weevil (Cyphocleonus achates) lay their eggs at the root of the plant for the larvae to feed on. The Yellow-winged knapweed root moth (Agapeta zoegana) and two species of Tephritidae flies (Urophoraaffinis and Urophora quadrifasciata) all help to contain Centaurea diffusa and also another invasive knapweed plant “Spotted knapweed”.
Physical control to remove knapweed is an effective way of controlling knapweed, although this is very labour intensive, as it involves digging up the long taproot to be effective. (Obviously this has to be done before the seed heads develop, otherwise you will be aiding the plant to disperse its seeds). Burning and cutting down knapweed is not always successful, because if the taproot survives, then the plant has a very good chance to recover.
Chemicals used in spraying knapweed can have a short-term control advantage, but some plants have shown to build up a resistance to this and in the long term these plants could prove to be harder to eradicate.
