Saturday, 21 July 2018
Tuesday, 10 July 2018
Sunday, 8 July 2018
Cassytha filiformis is a leafless, climbing, twining, vine-like, autoparasitic and plant-hyperparasitic phanerogam (seed-bearing plant) in the plant family Lauraceae.
The genus name derives from “kesatha”, Aramaic for ‘a tangled wisp of hair.’ The specific name “filiformis” is a Latin word for ‘treadlike’
Cassytha species are parasitic vines with small haustoria (infectious, adhesive structures used to withdraw nutrients from host organs through host cell membranes). Its stems are filiform, containing chlorophyll. The leaves are reduced to minute scales.
The flowers are sessile or pedicellate, in heads or spicate or racemose inflorescences; the floral tubes are shallow, enveloping the fruit; there are six persistent tepals, the outer three smaller than the inner three, nine fertile stamens, those of the third whorl with two basal glands, the fourth whorl reduced to staminodia; the anthers are dithecal.
The fruit is enclosed in the floral tube with a persistent perianth.
Seeds may be spread by animals, water, strong winds, farm machinery or with crop seed. The plant may spread locally by vegetative growth between hosts and over soils.
Seedlings of C. filiformis can survive for up to two months without a host and growing to a length of 30 cm or more.
The haustoria of C. filiformis penetrate the host epidermis and extend into more interior tissues, extracting cellular nutrients and water from plant phloem and xylem.
Even though the haustorium is an intracellular structure, it is not in direct contact with the host cell cytoplasm. In the case of phloem tissues, the cells of the plant host and the pathogen are separated by their respective cell membranes. Nutrients and fluid pass through these membranes. After the haustorium directly penetrates the cell wall, the haustorium does not penetrate or break through the plasmalemma membrane, but rather invaginates it.
The objective of C. filiformis is to obtain nutrients and water from the host plant without quickly killing host cells and without interfering in more than a subtle way with their activities; the pathogen does not create immediate, fatal damage to host cells and their metabolic processes. Rather, the host plants can die a long, protracted death by starvation and dessication, while C. filiformis, through intimate membrane-to-membrane contact with its host and with itself, extracts what is required for it to grow, flower and produce seeds for its future generations.
• Remove infestations manually as early as possible to prevent further colonization and seed production (for example, inspect host plants for C. filiformis and prune
the affected branches promptly).
• Herbicides may be available to kill the host plant or inhibit C. filiformis.
• Fire is used in some locations worldwide
• Shading can reduce the parasite’s vigor (C. filiformis is intolerant of shade).
• Graze sheep
• Slash clumps by hand with machete.
• Avoid planting C. filiformis-contaminated seed
• Control or destroy unwanted hosts of C. filiformis that are adjacent to plants or crops of cultural or economic importance in order to eliminate bridges between hosts.
• Minimize coastal habitat modifications such as bulldozing, forestry operations and firewood gathering.
• Reforest lowland coastal habitats (< 300 ft elevation) to increase shade.
• Do not collect soil for nurseries or gardens from the vicinity of C. filiformis-infected plants.