Sunday 6 May 2018

FLOWER OR ENEMY??

From a distance it looks so attractive, radiating warmth from its entangles of yellow vines that are intertwined in a conspicuous pattern...You can mistake them for Chinese noodles!



Is it an ornamental plant species not yet domesticated by aborists or florists??

No it isn't....

This is a parasitic plant!!!

Its name is Dodder or Field dodder. It is a very dangerous invasive plant species.

Golden dodder, ( Cuscuta campestris or tasmanica )is a parasitic plant belonging to the morning glory family.

The many species of Cuscuta(dodder) are leafless, rootless, parasitic plants with thread-like stems that coil around and attach to host plants.

Dodders lack chlorophyll, which is why they penetrate the tissues of host plants and steal their nutrients. Stems can range in color from white, to yellow and orange, and even to purple. Dodder bears small clusters of flowers in white, pink, or yellow in the summer months.



It is invasive in parts of Kenya, Tanzania and Uganda (CABI Crop Compendium 2007). Though the species is widely distributed throughout East Africa, there are few representative collections. In Kenya C. campestris is widespread at 1370-3000m altitude.

Cuscuta campestris seeds are dispersed by wind, water, birds, other animals, and by man on machines and planting material contaminated by dodder seeds.

Damage:

The plants have specialized adventitious roots(hausteria) that penetrate into the supporting plant and draw all needed nutrients and water there from.

Dodder is poisonous to animal and human beings read here.

Dodder can absorb toxins from the plants it feeds from. Many of these toxins can affect the liver and nervous system.

These are the signs of poisoning... 

Management of Dodder

Prevention

The use of dodder-free planting seed has long been a primary way of preventing the spread of dodder infestations.
Clean and inspect clothing and equipment before moving from infested to “clean” areas. Once you know an area is infested, you must manage it to prevent the further production of dodder seed. 
Isolate small infestations, and remove them by hand before the plant produces seed. Monitor larger infestations, and mow, prune, burn, or spray herbicides to prevent seed production.

Cultural Control

Planting nonhost plants can be an effective means of managing a dodder infestation. Plants that aren’t hosts of dodder include grasses and many other monocots including lilies. Plants that grow primarily during winter such as crucifers and legumes and transplanted trees and shrubs usually are good alternatives.

Dodder can’t penetrate tree bark, but it can penetrate tree foliage, if it is able to contact it. Be sure to remove weeds in these plantings, so the weeds don’t serve as hosts for dodder and increase the amount of dodder seed in the soil.

Dodder seedlings are difficult to find, but if you see them before they attach to a host, remove them by cultivation or hand pulling.

If you see dodder soon after it has attached itself to a host, prune the infected portion of the host plant 1/8 to 1/4 inch below the point of attachment, otherwise the dodder can regenerate from the haustoria left embedded in the host plant. 

If the dodder plants have set seed, remove the plants from the area to prevent future infestations. Place plants in a plastic bag, and dispose of them in the trash.

Dodder seed can survive soil solarization—a method for killing weeds using a clear, plastic tarp and the sun’s heat—probably because of its hard seed coat. 

Although studies haven’t been conducted, composting might kill most dodder seed, because higher temperatures are reached in the composting process than in solarization.

In agricultural settings, cultivate dodder before it attaches to a host plant, since cultivation done after dodder has attached itself to the host is of no benefit. Hand pulling, cutting, or mowing also can reduce dodder infestations. Be sure to break off, cut, or mow the host plant just below the point of dodder attachment (about 1/8 to 1/4 inch) for these methods to be effective. Close mowing is an effective management tool for dodder.

Burning reduces a dodder infestation as long as you destroy the invaded tissue of host plants along with the dodder to prevent regeneration of the dodder from embedded haustoria. Burning kills only some of the dodder seed; the amount of seed destroyed depends on the duration and intensity of the fire.

Biological Control

Several disease organisms are known to infect dodder including Fusarium tricinctum and Alternaria species, which attack swamp dodder(C. gronovii) , and A. alternata and Geotrichum candidum , which attack field dodder (C. pentagona) . 

Researchers in China have found that a suspension of Colletotrichum gloeosporioides can selectively control the dodder species C. chinensis and C. australis in soybeans. 

Breeding programs aimed at developing dodder-resistant varieties are not known to exist; however, some varieties of normally susceptible species have some resistance. Several varieties of processing tomatoes, a plant generally susceptible to dodder, have been observed to be either totally resistant or tolerant to dodder attack.

Chemical Control

Generally chemical control isn’t necessary in the home garden and landscape, since you can control dodder for the most part by cultivating seedlings or through hand removal or pruning. 

Although pelargonic acid (Scythe) is effective, it also kills any plant tissue it contacts; consequently good coverage and careful spraying are important, so desirable plants aren’t damaged.

Where dodder has been a persistent problem in certain commercial agricultural fields or in landscapes, apply preemergent herbicides (e.g., trifluralin) before dodder seed germinates; where practical, follow up with close mowing, burning, or spot removal of parasitized host plants to control dodder plants that escaped the herbicide application.


Usually postemergent herbicides, which you apply directly to the dodder plant to control it, don’t selectively control dodder without injuring the host plant and aren’t a good choice for controlling established infestations.


No comments:

Post a Comment

RAINWATER: THE UNTAPPED GOLD OF DRYLAND

RAINWATER IS THE GOLD WE WASTE IN DRYLANDS. For dryland farmers, harvesting water is as important as harvesting their crop. They need ...