Viruses

Viruses. Gall. Every grower will eventually have to deal with these unfortunate diseases... and every grower is going to need to decide their tolerance levels. 

Please allow me to share my thoughts, and please consider them before purchasing anything from Black Penny, or any other grower.

Lets begin with a very clear statement.... If you are seeking any kind of virus free guarantee, Black Penny Farms is not the farm for you. 

For Black Penny, gall is a do not pass go, it must be destroyed, nope nope nope. If you ever receive anything from Black Penny that you believe has gall, please contact me immediately, so I do not continue to ship what may potentially be ungrowable dahlias. Gall is always a reason to immediately trash a dahlia. Do not grow plants you know have gall. 

Then we come to viruses... this becomes more of a gray area... in a perfect world, all dahlias would be clean from all virus. But, this is not a perfect world. Black Penny follows all best practices... cleaning tools, wiping down surfaces, destroying any symptomatic plants, doing everything I can to keep plants healthy. Black Penny DOES NOT do routine virus testing, and never will. Knowing that the ADS recognizes that 80% or more of dahlias have at least one virus, this is not a war I believe can be won. Especially on the scale of this farm. 

Please understand that this does not mean I overtly grow sick plants. I do not. But, as long as a plant is asymptomatic, it can and will happily live here, because I do not test.

The problem with testing, is that its good for the moment the test is done. 2 seconds after I pull a leaf to be tested, an aphid could jump onto that plant and take a bite. So, while the plant could test clean, after that bite, it now may not. I cannot afford the cost or stress of constantly testing plants that appear healthy. 

Although it may seem like a recent phenomenon, virus infections in dahlias are not new. Viruses and dahlias evolved together. Wild species dahlias developed a tolerance for viruses that allowed both plants and viruses to coexist. However, once humans started selectively breeding dahlias, the traits favored by breeders had more to do with size, color, and form than with virus tolerance. Our modern cultivated dahlias are showier than their ancient ancestors; however, only some are prepared to thrive side by side with viruses.

Viral infections in dahlias are widespread, with recent studies showing an 87% infection rate in U.S. samples. Common viruses affecting dahlias include Dahlia mosaic virus (DMV), Tomato spotted wilt virus (TSWV), Impatiens necrotic spot virus (INSV), Tobacco streak virus (TSV), and Cucumber mosaic virus (CMV). These are spread from plant to plant by humans (using contaminated cutting tools) and insects, particularly thrips and aphids.

Symptoms of viral infection often result in mosaic patterns, ring spots, and vein chlorosis on dahlia leaves. Infected plants can also be stunted, bloom later than normal, and produce reduced-size blooms. Some infected plants appear to be asymptomatic and grow vigorously despite infection. Many growers can identify virus infection with visual inspections; however, laboratory testing or at-home test kits are the only way to scientifically confirm an infection.

Completely eliminating viral infections in dahlias is challenging and likely unrealistic. The goal should be to minimize impact rather than achieve total eradication.

Plant management strategies include:

1. Regular inspection and removal of symptomatic plants

2. Sanitation of cutting tools

3. Insect control

4. Proper disposal of infected plants

5. Purchase and propagation of virus-free cuttings

6. Growing from seed (first-year seedlings are mostly virus-free)

7. Strategic testing

Misconceptions about dahlia viral infections include:

• Rarity (they're actually very common)

• Possibility of complete eradication

• Plants "growing out" of infection (there is no cure)

• Soil transmission (viruses don't live in soil)

Possible areas of future research include:

• Less expensive testing method

• Genetic markers for virus tolerance for breeders

While the high prevalence of viruses may feel daunting, some infected plants are asymptomatic and will produce beautiful blooms and perform well in the garden. Growers should focus on overall plant health and vigorous plant growth rather than virus status alone.

This is a synopsis of a much longer section on dahlia viral infections from the book DAHLIAS: Seed to Bloom. This 278-page book covers all aspects of growing dahlias, including soil preparation, planting, pinching out, disbudding, seed propagation, making cuttings, pests, diseases, harvesting blooms, The Dahlia Genome project, and worldwide dahlia tourism. It also includes contributions from 9 top dahlia growers in 7 countries because there is no single "correct" way to grow dahlias. It is available on Amazon in softcover, eBook, or Audiobook.

So, what does this mean for a buyer? 

It means that I grow gorgeous plants, that show all signs of health, which is what you want in your gardens or fields, but, I will not state they are virus free. If they begin to show terrible virus symptoms, I will remove them. If they have one discolored leaf on an otherwise healthy looking plant, I will remove that leaf. I will be including an unedited picture of my rows of all varieties as part of their sale listing, taken once a month, and labeled. This will give any buyer the chance to "inspect" the healthy appearance of a variety before making a purchase. 

I do not take viruses lightly. I wish there was a way I could offer 100% virus free plants. But, I live in the reality that viruses exist in all species, and, if I'm going to lay awake in bed at night worrying about viruses, it will be concerning viruses in humans, not flowers.