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Phanerogamic plant parasites
1. Parasitic plant:
The plants which produce flower and subsequently bear seeds in
fruits and parasitized on other plants known as phanerogamic
plant parasites.
Haustorium:
It is a specialized projection / root like branch or organ of a
parasite that penetrates the host tissues and absorbs nutrients
and water from the host cells.
Phanerogamic parasitic plants
2. Phanerogamic parasitic plants
Stem parasite Root parasite
Holoparasites
(Entirely dependent)
e.g. Dodder on garden
ornamentals and hedge
plants.
Semi-parasites
(Partially dependent)
e. g. Loranthus on fruits,
wasteland, roadside and forest trees.
Holoparasites
(Entirely dependent)
e.g. Orobanche on tobacco, mustard,
brinjal, tomato, cabbage, cauliflower,
turnip and many other solanaceous and
cruciferous plants
Semi-parasites (Partially
dependent)
e.g. Striga on sugarcane,
cereals, maize and millets etc.
Classification of phanerogamic parasitic plants:
3. Parasitric plant: Dodder (Love-vine, Amarbel)
Scientific name: Cuscuta spp.
Dodder:
Dodder are the holoparasitic plants of jujibee, mango, some
ornamentals and crop plants. Dodder are non-chlorophyll
bearing, leafless, twining parasitic seed plants which attach
their yellow, orange or pink thread-like stems to the stems or
other parts of the cultivated or wild plants. They may be single
but are mostly conspicuous as tangled mass of intertwining
stems.
4. Overwintering and Dissemination
The dodder seeds, overwinter in infested fields or mixed with
seeds of the crop plants. The seeds may remain viable until a
favourable season returns. Portions of stem are also resistant to
adverse weather. The parasite may be introduced into a field and
spread by any of the following means:
• As impurity of the crop seed.
• As seeds and stem pieces moved by irrigation water.
• As stem pieces present on the dry straw from infested fields.
• As seeds in the manure.
• As stem pieces transported by cattle and farm implements.
• As stem pieces carried by birds or strong winds.
5. Symptoms on host plants:
1.Host suffers from malnutrition
2.Vitality of the host plant is reduced
3.Plant may be dwarf
4.Yellowing of the leaves with less flowers and fruiting
5.In case of severe attack, the whole plant of the affected part may
die.
6. A. Dodder stems entwined around stems of sunflower and
potato (B).
C. Dodder entwined around and overcoming a pepper plant.
7. D. Dodder covering and overcoming all watermelon plants in
an area of a field.
E. Dodder of the Lauraceae species Cassythia filiformis
spreading over roadside shrubs and trees in Florida.
9. Systematic position:
Class : Dicotyledonae
Order : Solanales
Family : Cuscutaceae
Genus : Cuscuta
Species : Cuscuta gronovii
10. Control:
Dodder can be controlled effectively by preventing its
introduction into a field by the-
1. Use of dodder free seed
2. Cleaning agricultural implements before moving it from dodder
infested field to new areas.
1. Limiting movement of domestic animals
2. Using of dodder free manure
3. Restricting the flow of irrigation water
4. Following a five year crop rotation with a non-host crop
5. Avoiding the dodder infested cattle fodder.
11. 1. Destruction of the crop by burning before seeding.
2. Chemical control by spraying herbicide like chemicals
e.g. 2, 4-D, PCP (pentachlorophenol) @ 0.3-0.4%
8. Cutting or burning of patches, will kill both dodder and host
plants but prevent dodder from spreading and from
producing seed.
12. Common name: Mistletoes/Banda
Scientific name: Loranthus sp/Dendrophthae sp.
Description:
Mistletoes are angiospermic semi-parasitic plant of fruit and forest
tree. In our country mango trees are the worst sufferers from this
parasitic. The parasite found on the tree as a dense cluster of
twigs and bears smooth green leaves and tubular flower. It has no
root system but develop haustoria into the host and intimate
association with vascular tissues. The green leaves posses
chlorophyll and synthesized carbohydrates. It depends on the host
only for water and minerals but do not totally depend on host.
13.
14. A. Male (yellow) and female (with fruit or seed capsules) dwarf
mistletoe plants growing on a pine branch.
B. Dwarf mistletoe plant parasitizing the trunk of a conifer (larch)
and causing it to swell and, later, to possibly break at the point of
infection. infections.
15. A. A Douglas-fir tree the top branches
and trunk of which have been killed by
dwarf mistletoe
16.
17.
18. Overwintering and dissemination:
The parasite overwinters as seeds. The parasite is spread by
dispersal of its seed mostly through birds and to some extent by
other animals. The birds are attracted by brilliant colour of the
fruit. Droppings of birds containing seeds also help in
dissemination of the parasite.
19. Symptoms on host plant:
1.Stunted growth of the host
2.Reduce the leaves size and may show unhealthy green colour.
3.Flowering and fruiting may be hampered.
4.Tumour may form on the infected area.
5.Quality and yield of fruit is considerably lowered.
20. Control:
1.Physical removal of the parasite by pruning of the infected
branches or by cutting and removing entire infected trees.
2.Detaching the parasite from the host in early stages of growth
without damaging any parts of the host.
3.If tumour is one side of the branch then the wood just below the
tumour may be sawed off.
4.Injection of copper sulphate sodium (25%) or 2-4, D (0.3-0.4%)
into the affected branches have been found effective on many
hosts.
5.Spray 30-40% diesel oil emulsion in soap water has been found
effective in eradicating the parasite from mango.
21. Systematic position:
Class : Dicotyledonae
Order : Solanales
Family : Loranthaceae
Genus : Loranthus/Dendropthae
Species : Loranthus sp. / D. falcata
22. Parasitic plant: Broom-rape
Scientific name: Orobanche spp.
Broom rape:
Broom-rape (Orobanche spp.) are total root parasites affecting
tobacco, mustard, tomato, cabbage, cauliflower, turnip and many
other solanaceous and cruciferous plants, which are especially
destructive to tobacco.
Description of broom-rape:
The parasite (Broom-rape) consists of a stout, fleshy, stem, 10-15
inches long. The stem is pale yellow or brownish red in colour and
is covered by small thin and brown scaly leaves. Flowers
appearing in the axil of leaves are white and tubular. The seeds
are very small and black in colour and may remain viable in the
soil for several years.
23. Broomrapes (Orobanche sp.) parasitizing various plants:
A. On fava bean
B. On broad bean.
C. Orobanche parasitizing the respective plants and destroying the
crop in a tomato field
24.
25. Orobanche parasitizing the respective plants and
destroying the crop
D. In a carrot field and
E. In a broadbean field
26. 2
1
Overwintering and Dissemination:
The parasite overwinters as seed in the 1 inches depth of soil.
Dissemination of seeds are carried out by rain water, birds and
even animals.
Development of parasitic relationship with host:
Broom-rape overwinters in the soil of the infested field. During the
growing season, the seed germinates and produces parasitic
nourishment from there. A large number of parasitic roots may be
seen breaking the soil around the host plants. When the host is
carefully uprooted, the parasitic roots are seen interwined with the
host root system.
Symptoms on host plant:
1. Growth stunted, malnutrition and dwarfness of the host
2. Flowering and fruiting reduced
3. Sometimes the host plant died
27. Systematic position:
Class : Dicotyledon
Order: Orchidales
Family : Orobanche
Genus : Orobanche
Species : Orobanche ramosa
28. Control:
1. Preventing the introduction of its seeds in new areas.
2.Planting non-susceptible crops in infested fields
3. Frequent weeding and removal of broomrapes before they
produce new seed.
4. Long crop rotation with non-host crops may be practiced.
5. Drying the soil for six months may help to eliminate the parasite
completely by reducing the soil population of the seeds.
6. Spraying the soil with 25% copper sulphate solution found to be
successful in destroying the parasite.
29. Common name: Witchweed
Scientific name: Striga spp.
Losses: Losses vary and may range from slight to 100%
Description: Striga is a semi-root parasite of mostly monocots
such as corn, sorghum, millet, upland rice, and sugarcane, but
also cowpeas, peanuts, other legumes, sweet potato, and
tobacco and wholly dependent on the host from germination
to flowering and reproduction.
The parasite is a small plant, 15-30 cm tall, with bright green,
slightly hairy stem and leaves. Usually these plants develop in
clusters around the stem of the host. The parasitic stem
appears branched, leaves are narrow , long, and in opposite
pairs. The flowers are small and usually brick red or scarlet
although sometimes may be yellowish red, yellowish or almost
white. Flowers appears just above the leaf attachment to stem
and are produced throughout the season. Seeds are formed in
pods or capsules, each containing thousands of tiny brown
seeds.
30. Overwintering and dissemination
The parasites survives through seeds which require a minimum
dormancy of 15-18 months. The short distance dissemination of
the parasite takes place by the seeds through rain and irrigation
water while floods and strong winds are the chief agents of long
distance dispersal of the seeds. The parasite is also disseminated
by contaminated tools and equipment and by contaminated soils
carried on farm machinery.
31. A. Witchweed plant in bloom parasitizing a corn plant.
B. Groups of witchweed plants parasitizing each corn plant
along a row in a field
Witchweed (Striga sp.) parasitizing plants
32. C. Corn plants parasitized by witchweed plants appear
stressed, wilted, and stop growing.
D. A different species of Striga parasitizing the legume plant
hairy indigo.
34. Symptoms
Affected plants remain stunted, wilt and turn yellowish. Death
may follow these symptoms if the plants are heavily
parasitized. Infected roots bear a large number of witch weed
haustoria which are attached to roots and feed on it. One to
several witchweed plants may be growing above ground next
to the infected plants.
35. Control
1.Weeding and intercultural operation can be successful only
when parasitized in early stages of the parasitic growth.
2. Keeping the field flooded for sometime and then draining out
the water also helps in control of the parasite.
3. Catch crops consisting of host plants may be planted to force
the germination of witchweed seed and, and the parasite can
be destroyed by ploughing or by the use of weedicides such as
2,4-D.
4. Trap crops, consisting mostly non-host legumes, may be used
to stimulate seed germination to destroy the Striga.
5. Field should be kept clean from weed host plants.
36. 4. Use of resistant cultivars, seed treatment with
herbicides of differential toxicity, and use of witchweed-
infecting fungi as a biological control are possible
control methods under investigation.
5. Soil drenching with 2-3% copper sulphate solution up
to a depth of 10-15cm can be done to control witchweed.
6. Soil fumigation with methyl bromide @ 0.01% is
effective against Striga spp.
