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Purple Power

Pest: Broomrape

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Pest: Broomrape

 

 

 

 

 

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(Orobanche ramose)

 

Special Species Notes

 

 

The broomrape is from a genus with over 200 species of parasitic herbaceous plants in the family Orobanchaeceae, mostly native to the temperate Northern Hemisphere.  Some species are often named after the plant they parasitise. An example, the Ivy broomrape, Orobanche hederae, only able to parasitise a single plant species, the Ivy. The broomrape is parasitic on other plants by draining nutrients from the host plant's roots, since they lack leaves and chlorophyll. Orobanche ramosa is a species of broomrape known by the common names hemp broomrape and branched broomrape.

 

This parasitic weed is native to Eurasia and North Africa, but it is known in many other places as an introduced species and sometimes a noxious weed. It is a serious threat for the production of several crops in Europe, Africa, and Asia. This species was introduced by humans to southwestern Australia, South and North America, South Africa, Mexico, and Cuba. In the U.S., it's in CA, TX, IL, KY, NC, VA, NJ.  Hemp broomrape is a worldwide noxious parasite of many crops and associated weeds. Heavy infestations can severely damage crops. Plants highly variable where native; less so in introduced populations.

 

 

It is an A-rated (“A”–Eradication, containment, rejection, or other holding action at the state-county level. Quarantine interceptions to be rejected or treated at any point in the state) noxious weed in California. In regions up to an elevation of about 160 feet (50 m).

 

 

 

 

 

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Branched Broomrape

 

 

Common Species:

 

 

There are over 200 different species of Orobanche

 

six severely parasitize crop plants that are the worst

 

Orobanche ramosa has a broad host range.

O. aegyptiaca

O. cernua

O. crenata

O. cumana

O. minor

 

 

 

IDENTIFICATION

 

 

Broomrape is an annual, biennial, and sometimes perennial parasitic plant depending mainly on its host. It attaches to plant roots and is visible above ground only when flowering and inhabits ornamental and vegetable crop fields and margins, especially tomato fields.

 

The entire plant lacks chlorophyll, so it is best recognized by its yellow- to straw-colored stems. It lacks conspicuous leaves, the leaves are merely triangular scales.

 

They have yellow, white, or blue snapdragon-like flowers. The flower shoots are scaly, with a dense terminal spike of between ten and twenty flowers in most species. These plants generally flower from late winter to late spring. When they are not flowering, no part of the plants is visible above the surface of the soil.

 

 They have dust-like seeds. The seeds are angular to egg shaped and yellowish brown, with a dull and netlike surface. The seeds color changes with age, tan-to-brown, and blacken. The seeds maintained at high moisture and high temperature, lose viability relatively rapidly. This could explain the success that has been occasionally reported from prolonged flooding or water-logging, but at least 6 weeks may be needed. Broomrape seeds remain dormant in the soil, often for many years, until stimulated to germinate by certain compounds produced by living plant roots.

 

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First signs:

 

Leaves  -  wilting

Leaves  -  yellowed or dead

Roots  -  reduced root system

Whole plant  -  early senescence

 

They don't cause very distinctive symptoms but may cause some wilting, yellowing and necrosis of the foliage and a general weakening of the plant, with reduced fruit production.

 

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Naked broomrape

(Orobanche uniflora)

 

Life cycle

 

 

Broomrapes do most of their damage underground.

 

Broomrape seedlings grow below ground. They put out a root-like growth, which attaches to the roots of nearby hosts. It drains nutrients from the host plant's roots by sinking there specialized roots (haustoria) into the host’s xylem and phloem to withdraw fluids and nutrients.  Once attached to a host, the broomrape robs its host of water and nutrients, and their haustoria provide portholes for root rot fungi. 

 

Only briefly do broomrapes send shoots above ground, which quickly flower and set seeds. The plant produces many slender, erect stems from a thick root. The aboveground parts are pale to bright yellow. The yellowish stems grow 4 to 23-6/10 inches (10-60 cm ) tall and are coated in glandular hairs.

 

Branched broomrape blooms from October through November. Flowers resemble small snapdragons-like flowers, ranging in color from white to blue or violet. Twenty or more flowers cluster to form a spike-shaped flower head. Upper flowers are stalkless and lower flowers are short stalked. Stems and flower heads are covered with very short glandular hairs. The fruit is a one-chambered capsule that opens by two valves at the tip.

 

 

 

 

 

 

Host plants:

 

Tobacco,  cannabis, hemp,  potato, especially tomato, carrot, aubergine, lentil,

oilseed rape (Brassica napus ssp. napus), onion, celery, groundnut bell pepper, safflower, caraway, chickpea, watermelon coriander, melon, cucumber, pumpkin, fennel, sunflower, lettuce, black medick, parsnip, pea, apricot, aubergine, fenugreek, faba bean, eggplant, coleus, beans

 

 

 

 

 

How it spreads:

 

Humans, machinery, water or wind can easily disperse these seeds.

 

 

 

What to do for preventative use

 

 

 

 

As a result of the direct connection to the host, a predominantly subterranean life and durable, numerous and small seeds, control of Orobanche spp. is very difficult by means of agronomic practices and the application of herbicides.

 

A more efficient way of limiting the effects of these parasitic angiosperms is the prevention of infection of plants and subsequent infestation of sori by developing resistant crops.

 

 

Hand pulling plants, plowing under trap crops before seed production, or burying seed with one deep inversion plowing can help control infestations. Trap crops may be used to promote germination of Orobanche seeds in soil, without themselves supporting parasitism, in order to deplete the seed reserve.

 

sterilizes your soil based on mulching moist soil with polyethylene sheets for several weeks under solar irradiation, can provide excellent levels of control of Orobanche seeds in the upper soil layers where temperatures are high enough.

 

avoid the use of Orobanche -infested crop seeds

 

High levels of nitrogen have been reported to reduce O. ramosa in tomato and tobacco, but in others the crop has been damaged and care is needed to maintain the correct balance between nitrogen and phosphorus.

 

Biological control

The fly Phytomyza orobanchia has been used for biological control of Orobanche spp., including O. ramosa, and was effective in the former Soviet Union for decades, using special rearing and Releasing of large numbers of natural enemies to effect immediate high mortality in release techniques. However, this became less effective due to the spread of hyperparasites.

 

Several Fusarium spp. and other plant pathogens have been reported specifically to attack O. ramosa but none have yet been developed fully for biological control.

 

 

 

 

 

The link below will take you to "An Intro to beneficial bugs, their food, and the pest they take care of"  it has a list (been worked on) to pests and beneficial insects

 

  http://freemygreenpdx.com/topic/14334-an-intro-to-beneficial-bugs-their-food-and-the-pest-they-take-care-of/


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