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Purple Power

Pest: Dodder

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Pest: Dodder

 

(Cuscuta campestris and Cuscuta europea)

 

 

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Cuscuta europea

 

Special Species Notes

 

Cuscuta (dodder) is a genus of about 100–170 species of yellow, orange, or red (rarely green) parasitic plants. Formerly treated as the only genus in the family Cuscutaceae, it now is accepted as belonging in the morning glory family (Convolvulaceae). The genus is found throughout the temperate and tropical regions of the world, with the greatest species diversity in subtropical and tropical regions; the genus becomes rare in cool temperate climates, with only four species native to northern Europe. Cuscuta campestris is a native to North America.

 

The genus Cuscuta does not occur at high latitudes in the Northern Hemisphere or in desert areas of Africa and Asia.

 

They can be found in common in disturbed areas, especially disturbed grassland, yards, open woodlands, coastal vine thickets, gardens, wetlands, surroundings of outhouses, waysides, streamside thicket. rail/road sides, urban, riverbanks.

 

Also known as strangle tare, scaldweed, beggarweed, lady's laces, fireweed, wizard's net, devil's guts, devil's hair, devil's ringlet, goldthread, hailweed, hairweed, hellbine, love vine, pull-down, strangleweed, angel hair, and witch's hair. Cuscuta europea common names are clover dodder and common dodder. Cuscuta campestris: field dodder, golden dodder, large-seeded alfalfa dodder, yellow dodder and prairie dodder,

 

 

Cuscuta campestris is highly attracted to "far red light", which is a wavelength that is reflected by most plant surfaces. Dodders that were exposed to unfiltered light were able to attach to their host before their energy had been totally exhausted, but dodders that were only exposed to red light lost their way, and died.

 

 

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Cuscuta campestris

 

 

Identification

 

Dodder have thin stems appearing leafless. Cuscuta europea stem is limp twining and may be up to 3-1/3 feet long. Its stems are hairless, thread-like (0.25–0.40 mm in thickness) and can be yellow, red or purplish in color. The stems wind counter-clockwise around the host plant as it grows. The leaves are triangular with rounded tip, pale brown.

 

The flowers are white to pink to yellow to cream. four- or five-lobed, 3–4 mm long. Corolla-lobes pointing obliquely upwards, and with rounded. The sepals come together to form a cup shape, each individual sepal being longer than it is wide. They are rootless. When growing on perennial hosts, Cuscuta epithymum induces the formation of galls (growths of host tissue) where parasitic tissue is able to overwinter. The following spring, new clover dodder plants develop from these galls.

 

Cuscuta campestris is a annual stem parasitic plant. It lacks normal roots and leaves, but does bear flowers and fruits. C. campestris stems are thread-like, yellow to pale orange to pinkish-yellow in color, are branched. The stems entwined around the host. It makes tendrils of similar appearance which form coils and haustoria (a specialized root-like sucker which penetrates a host to obtains water and nutrients from it.) C. campestris flowers are white or greenish, aggregated in groups of 3-8. flat-topped or convex flower cluster in which the uppermost flowers open first. The fruit is a light-brown, 2-4-seeded boll. Seeds are oval, light-brown or brownish, to 1.25-2.5 mm long, 1-1.5 mm wide.

 

 

Common Species:

 

There are six varieties of Cuscuta epithymum, which are distinguished by differences in their flower structure as well as the number of flowers and how they are grouped. direct contact enables rapid growth and is one of the reasons why Cuscuta species are the most rapidly growing parasitic plants. When growing on perennial hosts, Cuscuta epithymum induces the formation of galls (growths of host tissue) where parasitic tissue is able to overwinter. The following spring, new clover dodder plants develop from these galls. 

 

 

Cuscuta reflexa can photosynthesize slightly

 

 

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Cuscuta europea

 

 

Host plants:

 

Dodder ranges in severity based on its species and the species of the host, the time of attack, and whether any viruses are also present in the host plant. By debilitating the host plant, dodder decreases the ability of plants to resist viral diseases, and dodder can also spread plant diseases from one host to another if it is attached to more than one plant.

 

alfalfa, lespedeza, flax, clover, potatoes, chrysanthemum, dahlia, helenium, trumpet vine, ivy, petunias

 

C. europaea are entirely dependent on the host plants for nutrition. clover, ground elder, onion, alders mugwort, astragalus stipulatus, beetroot, hop, cannabis, hemp, hawthorn, mints, raspberry willows, stinging nettle, faba bean, common vetch

 

Cuscuta campestris alfalfa, tomatoes, carrots and cranberry cannabis, hemp

 

 

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Cuscuta campestris

 

 

First signs:

 

The presence of Cuscuta is always obvious from the twining stems and tendrils. Symptoms of damage are not especially characteristic, but reflect the very powerful sink effect created by the haustoria, resulting in reduced vigor and, in particular, poor seed and fruit development from the host plant.

 

 

Life cycle

 

 

Cuscuta have no chlorophyll, or only a reduced amount, and are not usually photosynthetically active. Only a few Cuscuta species still show residual photosynthesis. However, all Cuscuta species absolutely depend on a host plant to complete their life cycle, and Cuscuta can be considered an obligate holoparasite. Most often the parasite’s life cycle is completed earlier than the one of the host plant which leads to a premature death of the host plant and thus can cause crop damage.

 

The life cycle of Cuscuta begins with seed germination. Germinating Cuscuta seedlings depend on limited seed reserves. must find an appropriate host plant stem within the first few days. If a plant is not reached within 5 to 10 days of germination, the dodder seedling will die. The seedling has only a rudimentary root for anchorage.

 

The Dodder uses airborne volatile organic compound cues to locate their host plants. Further experiments demonstrated attraction to a number of individual compounds released by host plants and repelled by one compound released by wheat. Cuscuta campestris is highly attracted to "far red light", which is a wavelength that is reflected by most plant surfaces. Dodders that were exposed to unfiltered light were able to attach to their host before their energy had been totally exhausted, but dodders that were only exposed to red light lost their way, and died.  To find and catch potential hosts, Cuscuta recognizes plant volatiles as chemo-attractants which guide seedling growth and increase the chances of successful infection. They preferred healthy, green, fertilized and mature plant hosts over yellow or seedlings.

 

After finding an appropriate host plant, the first physical contact initiates an attachment phase. The parasite winds around and even develops pre-haustoria and tries to penetrate these hosts.

 

Important signals initiating and controlling this prehaustoria formation include mechanical pressure, osmotic potentials, and phytohormones such as cytokinins and auxin.  During this attachment phase, host cells in proximity to the Cuscuta haustoria respond with an increase in cytosolic calcium, detectable in host plants expressing aequorin as calcium. This increase lasts for about 48 hours after the initial contact. Cells of the sucker produce an adhesive substance that works as an effective glue. Within the tissue of the sucker, an intrusive organ (haustorium) develops and directly penetrates the host tissue to create a bridge between host and parasite.

 

The attachment phase is followed by the penetration phase as prehaustoria develop into parasitic haustoria that penetrate the host stem through a fissure. This breach is effected by mechanical pressure and is supported by the biochemical degradation of host cell walls. Cells at the tip of the invading haustoria form “searching hyphae,” which try to reach phloem or xylem cells of the host plant’s vascular bundles. After contact with a sieve cell, the searching hyphae grow around the cell like the fingers of a hand, and the parasitic cell surface interacting with the host sieve cell is enlarged more than 20 times. The branching haustoria invade the tissues of the host and satisfy the needs of the parasite by ‘stealing’ anything from water to sugars. The primordia of the haustoria develop on the inner surface of the twining stem. New haustoria develop close together wherever the dodder stem produces tight coils as it climbs up the host plant. These tight coils alternate with looser coils that search for new host branches or new hosts. They take more than 99% of its carbon and 93% of its nitrogen from the host. They will store the stolen nutrients just in case the host dies, so they can finish their life cycle. The root and shoot below this initial attachment soon die, leaving no direct contact with the soil.

 

Flowering and fruiting extend throughout the rest of the growing season, due to the indeterminate growth pattern. The flowers are white or greenish, aggregated in groups of 3-8.  C. campestris begins flowering around mid-July. C. campestris flowered only on flowering hosts. This suggests that flowering synchronicity may be determined by an“inhibitor flowering-hormone” produced by the host and traslocated into the parasite.

 

the Cuscuta europea  flowers are white to pink to yellow to cream. four- or five-lobed. Its flowering time is July–August. The seeds are very small and produced in large quantities. They have a hard coating, and typically can survive in the soil for 5–10 years, sometimes longer.

 

Species with small flowers are self-pollinating. Species with bigger flowers are pollinated by pollinators, or will self-pollnate if none are around.  Most of the flowers open in the morning, and a few during the day or at night. A single plant of C. campestris can produce 16 000 seeds.

 

 

How it spreads:

 

Seeds are dispersed by wind, water, by man, machines and planting material contaminated by dodder seeds, and unintentional import of seeds of C. epithymum in forage crops, birds, other animals (passing in their droppings).

 

 

What to do: For preventative use

 

Use of clean crop seed is vital. Seed crops which might have been infested should be inspected and cleaned if necessary.

 

Rotation with non-susceptible crops can be helpful. Cereals are virtually immune.

 

Deep shade suppresses the coiling and attachment of Cuscuta; hence encouraging a dense crop canopy is a valuable component of any integrated control program.

 

The young seedlings of Cuscuta, with rudimentary roots, are readily destroyed by shallow tillage before or after crop establishment.

 

Hand-pulling is suitable only for scattered infestations as the infested crop plants have to be removed with the parasite.

 

C. campestris have also been controlled by heat, using a hand-held flame gun

 

 

 

The link below will take you to "An Intro to beneficial bugs and beneficial insect food" 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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