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Digging Up the “Dirt” On Geraniums

Digging Up the “Dirt” On Geraniums

Everything You Need to Know About the Ralstonia Outbreak

As the month of April came to a close the United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) confirmed the detection of Ralstonia solanacearum race 3 biovar 2 (R3bv2) in a greenhouse in Michigan. The infection was discovered in a species of geraniums identified as the Fantasia ‘Pink Flare’ variety.

It has been roughly sixteen years since this bacteria was last found on U.S. soil and since then has garnered itself the classification of a potential bioterrorism agent against the United State’s agriculture. In 2004, Florida’s tomato crops were threatened by the disease and led to the destruction of over 4 million plants to prevent its spread.

How It Can Impact the U.S.

This specific strain of Ralstonia solanacearum has the potential to impact several important agricultural crops. However, it is potatoes and tomatoes that are at the greatest risk from this disease. Both agricultural crops are common hosts of the disease and can wipe out the entire crop with infection before the symptoms can be identified.

The bacterial wilt made its way to the U.S, this time, through an infected shipment of plants from Guatemala. Since its discovery, the foreign greenhouse responsible for the infection has voluntarily ceased all incoming and planned shipments to the United States. With an additional 288 greenhouses in 39 states who also received cuttings from this grower, APHIS has been working tirelessly to prevent the spread of this infection.

Who & What They’re After

The plant is targeted for eradication is the Fantasia ‘Pink Flare’ geranium. As the USDA moves through greenhouses affected by this disease they will go through and sample, isolate and destroy any of the species. Due to the spread of the infection that can occur between host plants and non-host plants, the USDA will also target other geranium species in the suspected greenhouses for the same methods of control.

How Does This Happen?

While the majority of Ralstonia solanacearum strains infect tropical and subtropical climates, the host of the bacteria ranges into the hundreds and can be located in agricultural goods around the world. It is in colder tropical climates that R3bv2 develops. The development of this disease is majorly identified in the highland, cooler tropical, parts of Africa, South America, and Asia. 
In an AmericanHort webinar, hosted for awareness of the disease, Professor Caitilyn Allen of Plant Pathology at the University of Wisconsin-Madison identified that the infectious tract for this disease is through the water-transporting xylem vessels. In a series of images she showed how, on a microscopic level, the bacteria infiltrates tomato stems and quickly takes over the healthy cells of the plant.

What To Look For

The most common symptom of this bacterial infection is stunting in plant growth. However, this disease can also be expressed by yellowing and wilting of the leaves, and eventually death of the plant. The University of Florida Institute of Food and Agricultural Sciences Extension states in their reporting of the bacteria that, “Symptom expression is favored by high temperatures (85°F-95°F). Symptoms of this disease may progress rapidly after infection, but plants may remain without symptoms for extended periods.”

The lack of symptoms that are in hosts makes the danger of this disease all the more pressing to the U.S. Agriculture. With the disease leading to a potato farmer’s nightmare, brown rot, it is truly a team effort of the industry to keep this disease from spreading.

It is additionally important to note that while there are symptoms that can help in identifying the disease, there are also a number of ornamental plants and Nightshade family weeds that can host the disease without symptoms.

Symptoms of Ralstonia solanacearum:

Here are a few ways to identify if your plants may possibly be infected:

  • Upward rolling of the leaves, that eventually leads to their collapse
  • When squeezing the stem of a suspected infected plant, a milky white ooze comes out
  • Placing a suspected infected plant stem in a glass of water and after 15 minutes milky streaking of bacteria is coming out from the stem

How to Move Forward

While there are testing options available, they aren’t 100% accurate in many cases and can be quite expensive to carry out. Instead, the USDA is recommending that if you believe your plants to be infected by the disease, or that you have received a plant of the known infected variety to reach out to the contact facility or report the infection through the USDA State Plant Health Directors page. They will schedule a date to come out to the facility and inspect the plants, as well as obtain some first-hand information. Following their scheduling, they will issue their “Emergency Action Notification” document with a more detailed version of the following procedures.

It is asked that you hold all plants of the Fantastia ‘Pink Flare’ variety, as well as any other geraniums or known host plants of the disease. This qualifies towards any host plants that may have been shipped between 10/2019 until 04/2020. The USDA also asks that you hold any plant material that may have been exposed or come in contact with the suspected infectious plants or any materials exposed to it.

The suspected material will then be tested. If test results are negative, then the items are free to be moved again. However if the material is found to be contaminated, then the items will be destroyed and the area disinfected through means that have been outlined to be acceptable by the EAN procedures of the USDA.

The Ending Our Industry Deserves

While growers and inspectors seek out infestation to destroy this disease once again from U.S. soil, it is noteworthy to mention that 55 Canadian greenhouses have also been infected from this incident.

As we look to the future from this occurrence, many are wondering how they can protect their crops from something like this happening again? Our answer is simple, Plant Sentry™.

When infections like Ralstonia solanacearum are discovered, Plant Sentry™ works to immediately notify our clients of the potential risks their plants face. This communication is essential in helping to slow the spread of the disease from the grower to the vendor. 


Early notification provided by Plant Sentry™ can reduce the potential exposure of the disease and may prevent the elimination of plants due to quarantine and destruction procedures by officials. We understand that every dollar spent should equal a dollar saved. At Plant Sentry™ we apply that mindset to protect your bottom line when a disease shows up to your nursery door. It is our responsibility as an industry to protect one another from the potential danger that a disease like this can cause. With Plant Sentry™ on your side, protection gets a whole lot easier!

To learn more about our efforts be sure to view our other blogs!

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VIRUSES & VIRAL PLANTS Pt. 3

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.