Details related tu Cuscuta spp

1. CUSCUTA AND ITS
MANAGEMENT
SUBMITTED TO – DR M.C. RANA
SUBMITTED BY – AKHIL BHARTI
A-2014-01-006

2. INTRODUCTION
Cuscuta (dodder) is a genus of about 100–170 species of yellow,
orange, or red (rarely green) parasitic plants. Formerly treated
as the only genus in the family Cuscutaceae, it now is accepted
as belonging in the morning glory family, Convolvulaceae, on the
basis of the work of the Angiosperm Phylogeny Group.

3. IMPORTANT SPECIES
 Cuscuta approximata
 Cuscuta californica
 Cuscuta epithyma
 Cuscuta europaea
 Cuscuta pentagona
 Cuscuta salina etc.

4. APPEARENCE
Dodder can be identified by its thin stems appearing leafless, with
the leaves reduced to minute scales. In these respects it closely resembles the
similarly parasitic, but unrelated genus Cassytha. From mid-summer to early
autumn, the vines can produce small fruit that take the same color as the vine,
and are approximately the size of a common pea. It has very low levels
of chlorophyll; some species such as Cuscuta reflexa can photosynthesize
slightly, while others such as C. europaea are entirely dependent on the host
plants for nutrition.
Dodder flowers range in color from white to pink to yellow to cream. Some
flower in the early summer, others later, depending on the species.
The seeds are minute and produced in large quantities. They have a hard
coating, and typically can survive in the soil for 5–10 years, sometimes longer.

5. PARASITISM
 After a dodder attaches itself to a plant, it wraps itself around it. If the host
contains food beneficial to dodder, the dodder produces haustoria that insert
themselves into the vascular system of the host. The original root of the dodder
in the soil then dies. The dodder can grow and attach itself to multiple plants. In
tropical areas it can grow more or less continuously, and may reach high into the
canopy of shrubs and trees; in temperate regions it is an annual plant and is
restricted to relatively low vegetation that can be reached by new seedlings
each spring.
 Dodder is parasitic on a very wide variety of plants, including a number of
agricultural and horticultural crop species, such
as alfalfa, lespedeza, flax, clover, potatoes, chrysanthemum, dahlia, helenium, t
rumpet vine, ivy and petunias, among others.
 Dodder ranges in severity based on its species and the species of the host, the
time of attack, and whether any viruses are also present in the host plant. By
debilitating the host plant, dodder decreases the ability of plants to resist viral
diseases, and dodder can also spread plant diseases from one host to another if
it is attached to more than one plant. This is of economical concern in
agricultural systems, where an annual drop of 10% yield can be devastating.

6. DAMAGE
 Impact varies from moderate to severe reductions of plant growth
and, in some cases, complete loss of vigor and death. The severity of
an infestation depends on the growth stage of the host plant at the
time of initial dodder attachment. With native dodder, the greatest
growth reduction occurs when the parasite attaches to seedlings; the
infestation usually doesn’t kill established host plants, but when
multiple attachments are made to the same host plant, death can
occur. Japanese dodder can cover and kill most large shrubs and small
trees. The weakened state of infected plants also predisposes them to
diseases and insect and nematode invasions.

7. MANAGEMENT
 Prevention
 Cultural Control
 Biological Control
 Resistent Varieties
 Chemical Control

8. PREVENTION
 The use of dodder-free planting seed has long been a primary way of
preventing the spread of dodder infestations. Many countries and states have
seed laws that prohibit the presence of dodder seed in planting seed.
 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.

9. 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. Pruning trees and shrubs generally has been
of little benefit unless dodder is confined to one or two branches that you can remove
without destroying or disfiguring the entire host plant.
 If no host plants are present, you can leave cultivated dodder plants on the soil surface
to dry and die. However, if you allow freshly removed dodder to contact a healthy host
plant, a new connection sometimes occurs. 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.

10. 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. Difficulty in culturing and
applying these organisms has limited their commercialized use.

11. RESISTENT VARIETIES
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.

12. CHEMICAL CONTROL
 Several post-emergence (POST) and pre-emergence (PRE) herbicides are
effective for dodder control/suppression.
 Common PRE herbicides (applied prior to dodder emergence) for dodder control
include Kerb (pronamide), Treflan (trifluralin), and Stomp (pendimethalin).
 POST application (applied after dodder emergence) of Dacthal (DCPA), Scythe
(pelargonic acid), Raptor (imazamox), Pursuit (imazethapyr), and Gramoxone
(paraquat) have been shown to be effective in dodder control/suppression.
Broadcast or selective (spot treatment) application of Roundup (glyphosate) also
has been shown to provide good control of dodder; however, spot treatments of
Roundup will result in crop injury in non-Roundup Ready crops.