Diseases caused by parasitic higher plants

2. A PRESENTATION
ON
Diseases Caused by Parasitic Higher Plants

3. 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 .

4.  Stem parasites:
 a)Holo parasites-cuscata spp.
 b)Semi parasites-Loranthus, Dendrophthoe
 2)Root parasites:
 a)Holo parasites-Orbanche
 b)Semi parasites: Striga spp.

5. Brief description about some parasitic higher
plants:

6. 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.

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

8. Fig(b):Dodders spreading in clover field.

9. 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.

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

11. 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.

12. Broomrape (orobanche spp):

13. 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.

14. Witch weed(striga spp):

15.  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.

16. 
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