A PRESENTATION ON

Diseases Caused by Parasitic Higher Plants

Introduction:Those seed plants living on another plant and

obtaining food, nutrients, water from it are parasitic higher plants .

These flowering plants attack valuable crops and trees causing considerable damage.

2500 species of higher plants live parasitically on other living plants. Most common plant parasites are mistletoes , broomrape , witchweed , and dodder .

TYPES OF PARASITIC HIGHER PLANTS:

Stem parasites: a)Holo parasites-cuscata spp. b)Semi parasites-Loranthus,

Dendrophthoe

2)Root parasites: a)Holo parasites-Orbanche b)Semi parasites: Striga spp.

Brief description about some parasitic higher plants:

Dodders(Love vine or knot weeds) are:• Non chlorophyll bearings, leafless parasitic seed plants which attach their

yellow, orange, pink, thread like stems to the stems or other parts of the cultivated or wild plants. A single plant may produce as many as 3000 seeds. Dodder is parasitic on a very wide variety of plants, including a number of agricultural and horticultural crop species, such as alfalfa,flax,clover, potatoes, chrysanthemum, dahlia, trumpet vine etc.

• Problems are: Reduced host plant growth, yield, and quality losses have been reported. Aside from a few small outbreaks, dodder is considered an oddity in agricultural production.

Figure(a): Dodder( cuscata europaea) in flower

Fig(b):Dodders spreading in clover field.

MISTLETOES They appears in cluster at the point of attack. Is a

common parasite of fruit and wasteland and roadside trees. Mangoes are worst sufferer from this parasites.

Since it is devoid of a true root system of its own. it is dependent on the host for nutrients. It obtain these by developing hausteria. The continuous absorption of nutrients by the parasite deprive the host from nutrients required for its own growth. Thus it causes branch withering.Main problems caused by them are –The quality

and yield of fruits is considerably lowered ,leaves may be re reduced in size and may show unhealthy green colors.

Mistletoes:

Fig(c): Mistletoe attached to Eucalyptus host Fig (d): Mistletoe attach to a silver birch tree

Broomrape (orobanche spp):• Orobanche – Annual or perennial, yellowish, brown or

purplish root parasites that lack of chlorophyll. Stems are simple or branched and fleshy; having bare scale-like leaves. they are about 15-50 cm tall. Seeds on these plant produces radicle which grows towards the roots of host plants.

• Problems: The host plants those are attacked by Broomrape are sweet pea, lettuce, snap bean, sunflower, and carrot. Parasitism by clover broom-rape may reduce host crop yield, and, in heavy infestations, kill the host plant.

Broomrape (orobanche spp):

Witch weed(Striga spp): Well known semi root parasite of sugarcane ,cereals ,maize and

millets. The parasite is small plant,(15-20 )cm tall, with bright green, slightly hairy stems and leaves. Usually these plants develops in cluster around the stem of the host. A Single plant of witchweed may produce 50000 to 500000 seeds. The viability of the seeds reported that( 12-40) years.

Striga is obligate root parasite wholly dependent on the host plant. It reduces the growth of the host plants. It increases the Respiration of host plants and decreases photosynthesis .Ultimately causes yield losses.

Witch weed(striga spp):

REMEDY/TREATMENTS: For remedy of diseases caused by parasitic higher

plants proper management is needed. Management generally includes some aspect of eliminating, removing or managing the host plant either physically or chemically. Seed lots can be examined or tested for purity to prevent transport of problems such as dodder and broom-rape. Silvicultural tactics are used for mistletoe management and include thinning, selective harvests, over story management, removal of brooms from individual trees and favoring non-hosts.

Although most of the plant disease are caused by fungi ,bacteria, viruses and nematodes ,there are a few diseases caused by parasitic higher plants. But sometimes higher economic loss can be occurred by parasitic higher plants. Because all the nutrients are up taken by them. Consequencely sometimes it may be threatening to our economy but proper management can maintain the loss at secured level.

conclusion