I had a positive test... Now what?

One of the most frequent questions our customers ask is “I got a positive test, what should I do now?”. The answer can be complicated and can depend on where, what and how you are growing. But no matter the situation there are several key methods to treat an infection, or even stop it if caught early. We will use botrytis as an example, but these steps are useful in addressing all diseases. 


First know what you are treating 

Botrytis (gray mold, bud rot, or bunch rot) is one of the hardest pathogens to control. It can be found almost everywhere and impacts more than five-hundred crop species. If you’ve never experienced an outbreak, it’s likely only a matter of time. It can spread easily through airborne spores from neighboring farms or by infected seeds and transplants.  


Botrytis also poses a particular threat to crops while in storage. So even if an infection doesn’t cause symptoms on your living plants, it will once they are harvested. Causing crop losses of more than US$10 billion annually. 


Proactive treatment works best 

Catching botrytis as early as possible is the main key to treating it successfully and preventing crop losses. We have developed CRD™ Botrytis to help find the pathogen as early as possible. It is a rapid in-field detection test that can detect spores or a hidden infection weeks before symptoms appear. Early detection can also be done visually by using a spore trap and culturing the sample.


Check the environment and plant nutrition 

Like all plant diseases, botrytis requires two other factors to cause an outbreak – the right environment and a susceptible host plant (Read more here – Understanding the Plant Disease Triangle). Controlling these factors will help prevent an outbreak even if botrytis spores are present. 


Creating a preventative environment – Botrytis thrives in cool and moist conditions. Do your best to eliminate these factors and create an inhospitable environment for it. Start with airflow, poor airflow allows early morning dew to increase moisture and can lead to spore germination. In greenhouses, you can raise the heat and open ventilation for 5-10 minutes to reduce moisture. Planting and pruning plants to encourage adequate air flow is another key form of control.  If you had a positive early detection test before pruning you might consider using a precise application of fungicides on the cut as botrytis can enter the plant there (more on fungicides below). Also clean up any dropped leaves or dead plant matter so botrytis can’t grow on it. 


Maintain plant health – Plant health and nutrition are also important to avoiding disease. Healthy plants with the proper nutrient inputs will resist and fight off infections naturally. In a study published in 2020, demonstrated that foliar treatments of calcium were effective in treating botrytis.  


“The results showed a 96% reduction in botrytis blight severity as Ca concentration increased from 0 to 1200 mg·L⁻¹ Ca”

With fungicide resistance becoming a bigger problem, focusing on your plants’ nutrient requirements and adding foliar treatments has great promise to fight botrytis issues.  


Using biologicals and chemicals 

If the disease persists or has appeared visually it requires more rigorous measures to control the damage. Botrytis will appear visually as a distinct gray hued velvety mass or sometimes as lesions on fruits. A rapid test can be used to confirm if botrytis is the culprit. 


Start by removing any leaves or plant tissue exhibiting signs of disease. Make sure to remove them completely as they are still infectious. Next apply a fungicide, there are sulfur and copper fungicides that are relatively inexpensive and higher-cost synthetic ones. Check with your local ag extension office on the best strategies and products for your region. Botrytis can develop resistance to certain fungicides, so it is important to stay informed to get effective use.   


New advancements in biological controls are also showing great results in the control of pathogens. Just like humans, plants have a native microbiological presence that acts as a first line of defense against pathogens. Biological controls use microbes and microbial compounds to mimic this symbiotic relationship and can significantly reduce pathogen severity. Your local ag extension office will be able to help you identify these solutions as well. 



Remember, rapid tests can be used to confirm the culprit is botrytis and to check whether treatments have been effective. If you want to learn more about early detection testing or aren’t sure whom to talk to in your area, please reach out to us Cubed Labs, we’d love to help. 

Interested in learning more or want to hear what Cubed Labs is all about? Schedule some time to talk with us!

Our own Brent Nichols would be happy to help – Click Here to schedule a meeting!

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