Orchids are treasured by their consecrated patron for beauty , novelty and longevity . Many collections culminate in decades of financial , temporal and emotional investments . Moreover , big - box retail vent and garden centers have introduced tiro to these alone plants by making orchid refinement available to the world-wide public at a reasonable cost . Availability and affordability have made the orchidaceous plant sphere one of the most economically important for the indoor plant market . orchidaceous plant are comparatively free of disease ; however , 30 different viruses are show infecting this family of prized plants . Many of these virus cause symptom presently after infection occurs , impacting artistic note value , whereas others remain concealed for years within asymptomatic specimens .
by Robert S. Emmitt
Once infected with a virus , an orchid remains infect for life history as no healing therapies exist . Therefore , the most effective stair in computer virus management is exclusion of viruses altogether . symptomatic examination is paramount to identification of infected plants preceding origination into cherished collection . Viral screens for orchid offered at examination science lab typically include nine viruses ( Table 1 . ) . Moreover , many commercial products are available for purchase , allowing collectors to perform on - land site testing . No matter the preferred testing option , growers should consider all suspects to make informed disease management decisions .
cymbid mosaic computer virus ( CymMV , Potexvirus ) and Odontoglossum ringspot virus ( ORSV , Tobamovirus ) are the most widely deal out viruses infect cultivate orchidaceous plant . Both viruses occur worldwide and have severe disease in several orchidaceous plant genera . Moreover , due to similar epidemiological properties , CymMV and ORSV are often transmit together , cause binary infections . Consequently , aggregation are most frequently screen for the presence of these virus , often simultaneously with a single Cartesian product . Both virus are stable excluded from host and transmitted efficiently via plant life - to - plant contact of septic plant sap , during activeness such as pruning , re - potting or dividing plants . longsighted - distance dispersion is through shipment of septic vegetative materials and seed as no arthropod vectors have been identify for either computer virus . Both computer virus infect orchid alone .
Figure 1 . symptom of ORSV on foliage of Cattleya specie ( look-alike courtesy of Terry Bottom , St. Augustine Orchid Society )
Symptoms of CymMV include greensick or necrotic streaks on foliation , oft in mosaic blueprint . Moreover , sink necrotic lesions can occur on leave of absence , resemble symptoms observed in correlation with fungal infections . Color break and necrotic spots can occur on flowers , but newly open flowers rarely demo symptom . Symptoms cause by ORSV infections include greensick or necrotic ringspots and streaks on leaf and color break on bloom ( figure 1 . and 2 . ) . Moreover , foliage with typical meek red or violet color can manifest uttermost red pigmentation . Mixed contagion can exasperate symptoms of both virus ( Figure 3 . ) , whereas less obvious symptoms let in stunt , decreased efflorescence and overall loss of vim . Symptoms are not definitive symptomatic tools ; however , their presence is indicative of physiological disfunction , actuate analysis . Unfortunately , CymMV and ORSV can cause latent infection , and infect plants can serve as asymptomatic reservoir of inoculum .
Figure 2 . Color break symptom on orchid flowers because of ORSV transmission ( Image courtesy of Terry Bottom , St. Augustine Orchid Society )
Orthotospoviruses known to taint orchids let in Impatiens necrotic daub virus ( INSV ) , Tomato descry wilting computer virus ( TSWV ) and Capsicum greensickness computer virus ( CaCV ) . Symptoms due to the type computer virus of this genus , TSWV , were first observed on tomato in 1915 . Since then , several additional members have been characterized . All three viruses are carry , or vectored , by multiple species of thrips ( Order Thysanoptera ) in a lasting , propagative manner . Thrips feed on a wide range of plant species , include many coarse herbaceous perennial and annual horticultural crops planted by homeowners .
digit 3 . Symptoms of a interracial contagion of CymMV and ORSV on Dendrobium species ( Image good manners of Terry Bottom , St. Augustine Orchid Society )
The Orthotospoviruses are known to infect over 1000 species of plants throughout the world , work for a long list of potential carriers . Many weedy specie such as common chickweed , Stellaria media , can be infected and remain symptomless , acting as reservoirs of virus when cultivated hosts are not available . mechanically skillful bed covering of these viruses is less efficient than with CymMV and ORSV , but happen , nevertheless . Symptoms of INSV and TSWV on orchid let in stunting and chlorotic ringspots arranged in discrete homocentric circles form a target slur or bull’s - eye visual aspect . This is due to the feeding patterns of thrip , and symptoms demonstrate at the point of contagion . These spots can coalesce and organise sunken necrotic lesions .
Multiple Potyviruses have been name cause disease in orchids . The type member of this genus , Potato computer virus Y , was first characterized in 1931 , and it is not be intimate to infect orchids . Potyviruses known to taint orchidaceous plant include Bean yellow-bellied mosaic computer virus ( BYMV ) , Clover yellow vein virus ( ClYVV ) , Dendrobium mosaic virus ( DeMV ) , Phalaenopsis chlorotic smear ( PhCSV ) , Turnip mosaic computer virus ( TuMV ) and Vanilla mosaic virus ( VanMV ) . Like the Orthotospoviruses , the Potyviruses infect more than a thousand works mintage , and with more than 150 characterized members , Potyvirus is one of the large genera of plant life viruses .
The Potyviruses are transmitted by multiple species of aphids ( Order Hemiptera ) in a nonpersistent style . This means the computer virus can be acquired from an septic plant via feeding , within seconds of stylet insertion . Shortly thereafter , the virus can be transmitted by the vector to level-headed plants . This is in dividing line to persistent transmission , such as that observed with the Orthotospovirus - thrip family relationship . Acquisition of virus by thrip can take several hours , and several days before transmitting is possible . Potyviruses are also send mechanically and through cum . Symptoms of Potyvirus infection on orchidaceous plant include greensick spots on foliage and color break on flowers . Leaf and blossom optical aberration symptoms have also been observed .
In addition to the virus mentioned above , several are love to taint orchids . These admit those beam by nematode , such as Tomato ringspot virus ( ToRSV , Nepovirus ) and Tobacco rattle computer virus ( TRV , Tobravirus ) . roundworm are not predominant in epiphytic bark substrate , and terrestrial orchids are at high jeopardy of transmitter - transmitted infections . Nevertheless , both virus are spread efficiently to epiphytic species via mechanically skillful vaccination . extra viruses confirmed to infect orchids include Cucumber mosaic virus ( CMV , Cucumovirus ) , Carnation mottle computer virus ( CarMV , Carmovirus ) , cymbid ringspot computer virus ( CymRSV , Tombusvirus ) and Orchid fleck computer virus ( OFV , Dichorhavirus ) .
The symptoms of several viruses are similar and can mimic abiotic result , such as those triggered by nourishing imbalance or environmental variability . Therefore , designation of the suspect pathology through diagnostic examination is the cornerstone of an in force virus direction program . examination can be carry out at university diagnostic laboratories or private examination installation . Many private science laboratory proffer virus examination screens as show in table 1 . , providing a way to test collection for multiple virus simultaneously . Moreover , several commercial ware such as Agdia ’s ImmunoStrip ® allow collector to test their plants at menage .
Regardless of the examination method acting , accurate diagnosis is the issue . That diagnosis is a data point to be used in the determination - making process , prompting action . Orchid collection represent sizable investiture in money , time and emotion , and many plants are historically meaning . The cost of precise diagnosis is an important part of the investment , promoting level-headed collections for twelvemonth to come .
For more entropy : AgdiaRobert Emmitt[email protected][email protected]www.agdia.com
