Description about algae and phanerogamic plant parasites which are also responsible for plant diseases, are described in easy and simple manner

1. ALGAE
AND
PHANEROGAMIC PARASITE
N.H. SHANKAR REDDY
2ND PH.D. PLANT PATHOLOGY
ANNAMALAI UNIVERSITY

2. Red rust of guava – Cephaleuros
parasiticus
Symptoms
• Disease symptoms are exhibited on both abaxial and
adaxial leaf surfaces as orange, rust-colored, dense silky
tufts ranging from 5 to 8 mm in diameter.
• These spots usually come together to form large irregular
patches on a leaf. As the spots mature they take on a dull,
grayish green color.
Management
• Algal leaf spot can be reduced by maintaining tree vigor
with cultural techniques such as proper fertilization and
irrigation, proper pruning to enhance air circulation
within the canopy and sunlight penetration, managing
weeds and wider tree spacing.
• Spray Copper oxychloride 0.25%.

3. Red rust of mango – Cephaleuros
virescnes
Symptoms
• Algae attacks foliage and young twigs.
• Rusty spots appear on leaves, initially as circular,
slightly elevated, coalesce to form irregular spots.
• The spores mature fall off and leave cream to
white valvet texture on the surface of the leaves
Management
• Bordeaux mixture (0.6%) or Copper oxychloride
0.25%

4. phanerogamic parasite
• The pathogenic flowering plants, also called parasitic angiosperms can be classified
as root parasites or stem parasites.
• Root parasites (witchweed and broomrape) are more common and more diverse
taxonomically.
• Stem parasites include the dodder (Cuscuta) and mistletoes (Arceuthobium).

5. Cuscuta
Cuscuta is a slender, yellow thread like, and produced white,
yellowish or pinkish colour flowers and absorbs nutrients
through haustoria. (here the cuscuta produce rudimentary
flowers)
o It belongs to the family Convolvulaceae
Hosts - More than 100 species of cuscuta are attacking on
trees, the main hosts include, clover, onion, alfalfa, potatoes,
sugar beets and ornamental crops
Management
o Use of dodder free seeds
o with host plant can prevent further spread.
o Application of contact herbicides 2,4-D, pentachlorophenol
o Crop rotation for 4 to 5 years should be adopted.

6. Loranthus
Lorathus is a partial stem parasite, mainly infects
coniferous and forest trees. It produce wedge shaped
haustoria and continuously suck the nutrients from host
o In Sanskrit it is called as “vrikshabhaksha” (plant eater)
o It belongs to the family Loranthaceae
Host - Fruit trees and forest trees
Management
• Hand picking of parasite at early stages of its growth or
cutting and removing of the infected trees.
• Injection of copper sulphate and 2, 4-D into the affected
branches have been found effective.

7. Orobanche
Orobanche is a complete root parasite affects herbaceous dicotyledonous
crop plants, shows symptoms of small patches, yellowing of leaves and
stunted growth
It belongs to the family Orobachaceae
Host – Sunflower, tobacco, tomato, brinjal, carrot, cabbage, lettuce, fava
bean, broad bean and sunflower
Management
• Prevent the introduction of seeds from new areas and avoid cultivation of
susceptible crops
• Use of resistant varieties
• Spraying the soil with 25 % copper sulphate solution found to be
successful.

8. Striga
Striga is a partial root parasite which parasite roots of the host, contains
green slightly hairy stem and leaves, doesn’t grow beyond 30cm high. The
affected plant parts are remains stunted, wilt, yellowish and killed the host
in severe cases
• The flowers are small and appears in red, white, yellow, pink colour
produced on aerial parts
It belongs to the family Scorphulariaceae
Hosts – It attack mostly monocots such as maize, sorghum, pearl millet,
sugarcane, cowpea, sweet potato, tobacco and peanuts
Management
• Uprooting and destruction of parasitic plant before flowering
• Flood irrigation is effective in eliminating the parasite.
• Use of witch weed infected fungi as biological control

9. Plant parasite Other names
Complete stem parasite Cuscuta (Golden vein, Dodder)
Partial stem parasite Loranthus/ Dendrophthoe (Gaint
mistletoe, Banda)
Complete root parasite Orobanche (Broom rape, Tokra)
Partial root parasite Striga (Witch weed)