VIRUSES & VIRAL PLANTS Pt. 3

As we’ve made our way through the past few blogs, we’ve examined the complex nature that viruses have. We’ve gone in-depth into the realm of viruses and examined two of the most unique virus families in biology. Now, we’ll examine the third and final family of viruses that have the capacity to infect the Animalia and Plantae Kingdoms.

The first of these viruses was the Bunyaviridae and the second was the Rhabdoviridae. The third of these rare viruses that we will be discussing is the Reoviridae family.

As we come to a close on our examinations of rare plant viruses that can infect humans we take one more close look at the dangers these species present.

Reoviridae

The Basics

Reoviridae has 2 subfamilies that have 15 genera that divide out into a total of 75 different virus species that infect a variety of hosts, including plants and animals. This virus family is the largest family of double-stranded RNA viruses, and perhaps the most understood of their kind. They have been identified in a wide variety of organisms, found in everything from an arachnid, a plant, fungi, reptiles, mammals, and more.

In humans, this viral family is responsible for the commonly known Rotavirus. The Rotavirus is passed from fecal matter being transmitted orally through contaminated objects and surfaces. This transmission encourages easier spread amongst children and infants.

But the Reoviridae viruses aren’t exclusive to humans. As mentioned above, the variety of hosts for these viruses almost seems unlimited, even infecting fish! But our major concern is the relationship these viruses have with plants and how we can prevent their spread.

Affect on Plants

Out of the abundance of Reoviridae viruses that exist, there are 3 genera that have approximately 14 different species that infect plants. These three genera are Phytoreovirus, Oryzavirus, and Fijivirus.

These viruses are believed to originate in ancient invertebrates and are developmentally reliant on the vectors of leafhoppers. Without the hoppers the virus could not reproduce in most cases and would die off completely. But, with the hoppers as the host, they are able to spread their diseases to different plant vectors. Due to the lack of spread through seed, many of these viruses reproduce through larvae of the hoppers and not just in the host themselves.

These viruses are mainly a threat to what are known as cereal crops and include rice, maize, sorghum, and barley. Each variation of these viruses affect each crop a little differently, but overall causes severe damage. As we examine these three different viral genera we should keep in mind how each of them could impact our environment if not properly managed.

Phytoreovirus

This virus produces the commonly known diseases of Rice Dwarf Virus and Rice Gall Dwarf Virus. Plants that are infected with these viruses exhibit defined stunting, more tillering, and leaves that are short and dark with chlorotic specks. The plants most often survive until harvest, but at that time it is often discovered that the flower containing the grain is empty.

The damage from these viruses are mostly experienced in Southeastern Asia, but that doesn’t mean it can’t affect other areas of the world. Diseases can often go unnoticed with little symptoms to the plant until harvest time.

This furtiveness can make the management of these pests and diseases almost impossible if not properly maintained. Cleanliness is of the utmost importance when managing stock plants. As part of Plant Sentry’s mission, we maintain constant vigilance on diseases like these to keep our growers informed and their plants healthy.

Orzyavirus

The second genera of the Reoviridae virus family to infect plants is the Orzyavirus. One of its species is the Rice Ragged Stunt Virus. This disease is transmitted by the Brown Planthopper and reduces the amount of plant density and grain production. This virus is most commonly found in tropical Asian climates where the conditions are optimal for continuous habitation of the Brown Planthopper and rice to be grown all year long.

Much like the Phytovirus the threat that this disease poses to crop quality and density is significant. While it primarily occurs in other parts of the world outside the United States, it still has the potential to impact our food supply and the plants that we grow. It is oftentimes that once a species makes its way to our country that a virus or disease mutates and infects its new surroundings differently than it had in its original habitat.

Fijivirus

The last genera of this viral family is the Fijivirus. In recent years these viruses have primarily been found targeting rice production in China. But many years before, they were found to be ruining sugar crops in Australia.

Currently, the Southern Rice Black-Streaked Dwarf Virus is transferred by the White-Backed Planthopper and causes damage to rice crops. The earlier the plant is infected, the more damage that is done.

Similar to the other diseases we’ve reviewed today, this virus can cause dwarfing, stiffening of leaves, lack of grain production, and increased tillering. The infected plant leaves are often dark and short with some ruffling on the edges.

Like so many other diseases, every component of its management can potentially affect its neighbor. As we’ve seen in recent months, all it takes is one vector to carry disease to a new environment and create a dramatic impact. Habitats and ecosystems may vary from place to place, but many of these species are genetically designed to thrive on its unsuspecting victims.

How It Affects You

As we come to a close with our examinations of viruses, we hope that this has made you more curious and considerate of how viruses can infect our world. Where we once thought viruses to be limited, maybe now we’re a little more open-minded on just how easily they can spread. As the world reemerges from its quarantine cocoon, we recognize that our perception of viruses has changed, hopefully for the better.

At Plant Sentry we plan to use our new-found knowledge to help our growers achieve optimal plant health. We work around the clock to provide our clients with the highest level of awareness against disease and pests. Through our expertise in disease management we know the best practices that will make work easier on growers for seasons to come. In this ever-changing world, there has never been a better time to do the right thing and keep your plants safe and healthy. To learn more about our practices visit the Our Services page and see why what we’re doing makes a BIG difference.

The Seriousness of Sudden Oak Death

The Midwest, previously safeguarded from the detrimental disease known as Sudden Oak Death, has now suffered a critical disaster.

In the state of Indiana, the Department of Natural Resources discovered several varieties of infected rhododendrons, which are believed to have originated in the Pacific Northwest. The West Coast is an area commonly impacted by the disease. The plants were sold in over ninety stores across the state, transferring contaminated material not just between Indiana counties, but to nine other states as well. These states had been unaffected by Sudden Oak Death before the incident.

Sudden Oak Death is a fungal disease that quickly eradicates healthy oak species. Additionally, over one hundred other plant species are vulnerable to infection. These species are capable of transferring the disease to any oak planted within a six-foot range. The fungus can be transported by the wind, making it even more dangerous to the environment. No treatment exists.

Why Is Sudden Oak Death So Serious?

First, the introduction of the disease to Indiana won’t simply destroy the state’s oak trees, but it now has the power to kill off oaks in other states that received infested shipments.

Second, Indiana’s Department of Natural Resources has to go through an extensive process to track and eliminate the infected plants from the shipment and also deal with infected oaks if this would occur. This involves inspecting any possible host plants that may be carrying the disease, too. Currently, over 1,500 rhododendrons have been destroyed, and approximately 1,500 more are being quarantined.

Third, shipment of any more plant material from the nurseries held responsible must undergo thorough examination to prevent further spread of the disease. Most importantly, however, the introduction of Sudden Oak Death could persist and result in future devastation, both economic and environmental.

Large sums of money are necessary to track and eliminate the infected varieties, as well as any discovered host plants. Stores that had been selling these plants may suffer business losses from frightened customers, too.

Even more, though, the death of thousands of oaks could negatively impact the lumber industry long-term. Oak is an expensive lumber material, and trees are a top value crop in Indiana among other states. With significantly fewer oaks, the lumber industry will suffer an extreme loss.

Finally, the death of these oaks will take away one of the most majestic trees in the nation. As oak trees age, they give a beautiful appearance, gracefully towering over their surroundings. Oaks are one of the most known historic plants, often complementing parks and plantations as well as the local landscape.

As seen, Sudden Oak Death has the power to devastate. With such great concerns for both the environment and economy, raising awareness of serious plant diseases is crucial. As consumers, tree-huggers, and everyday people, we should all take with us an important piece of information: spread of pests and disease is detrimental, and it is also preventable. Promoting awareness of such disasters as Sudden Oak Death is simply the first step in solution.

References:

Indianapolis Star Article on Sudden Oak Death

Nursery Management Magazine