Field day participants discuss disease management with Farmer Anton Shannon, at Good Work Farm.
Do what you can to prevent disease from the beginning of the season, especially if you are an organic grower who has a limited reactive toolbox, or someone who wants to reduce their use of pesticides in general.
Use new field materials, that haven't been exposed to disease
For example, use new wooden stakes each year for crops like tomatoes. Porous wood can harbor disease from one season to the next and infect your crop.
From greenhouse to field, make sure your plants have a clean environment to get them off to a better start. Sanitize your greenhouse and use new, or properly cleaned flats each season.
Choose disease resistant varieties
Seed companies and breeders work hard to develop these new varieties. Take advantage! Cornell keeps a catalog of resistant varieties.
Rotate crops and improve soil health
Keep crops on a rotation of 3 years or more and utilize practices such as cover cropping to help break disease cycles and improve overall soil health.
Use crop specific tools, such as hot-water treatment for seed
Heat treating solanacea or brassica seeds helps reduce seed borne bacterial diseases from the start.
Read more about hot-water treatment.
Use cultural controls
Provide proper spacing between rows and plants, reduce weed pressure through cultivation and weeding, and utilize trellis methods such as the Florida Weave on tomatoes to improve airflow and reduce overall disease pressure.
Follow a preventative spray schedule
A preventative schedule can be an effective control for diseases that make an appearance every season. Disease forecasting tools such as NEWA Tomcast, IPM PIPE and USABlight can help you schedule, and in the end reduce overall sprays and crop damage.
Scouting is one of the most important tools for disease prevention.
Regular scouting helps you find a problem before it is too late. It can help you determine when it's time to take action, or when things are okay and you don't need to do anything.
Early and often! If possible, scout each crop once a week. If you're working your fields every day, pay attention to catch early signs and symptoms.
Get into your rows and beneath the plant canopy. It's important to get close to your crop and look at plants distributed evenly throughout the field. Select plants in a zig-zag pattern, and be sure to look at lower leaves, as well as the undersides of leaves. Pay attention to problem areas (wet, low lying), but don't focus on them entirely. In addition to walking the field, look closely at a few leaves per plant on at least 10 plants distributed throughout the plot.
Important scouting tools
Make sure you have everything needed with you when scouting. Keep a scouting bag ready with a notebook and pen, camera, 10x hand lens, trowel, pruners or knife, plastic bags for leaf or plant samples, and some good disease identification resources.
If it looks like there's a problem out there, it's time to get down to your detective work. Know what questions to ask and the resources available to identify the problem.
Does it seem like the problem started at one end of the field and is working its way down row? Is it distributed randomly throughout the crop? Did it start at one point, and radiate out?
Did the problem seem to spread slowly over time, or did it affect the whole crop at once.
Consider abiotic possibilities
Was there a recent weather event that may have affected the crop? Could it be related to nutrition or irrigation?
Make note of signs, or actual visuals of the disease, such as spores. Record all visible symptoms, or how the plant seems to be reacting (yellowing/browning, wilt, etc.).
Consult disease identification resources
Once you have the necessary information, start doing some research to determine what the problem is. Disease compendia and guides such as the Northeast Vegetable and Strawberry Disease Identification Guide, Identifying Diseases of Vegetables , as well as Cornell's Vegetable MD website are just a few of the tools available to help you.
When in doubt, send a sample to the lab
Sometimes, even the experts have difficulty telling various diseases apart. Send a sample to a lab such as the Penn State Plant Disease Clinic. Their website provides submission forms as well as instructions.
A Plan of Action
Once you've determined the problem, you can put together a plan of action that works best for you.
If the problem is caught early enough, sometimes rogueing out affected plants and using cultural controls to reduce pressure can be enough.
If the problem is more severe, consult production resources such as the Pennsylvania Commercial Vegetable Production Recommendations , or the Cornell Organic Production Guides, to determine what chemical or biological controls are available.