Four things to remember with nursery disease issues
Pots, trays, media and seeds are ready to go. And so are the pests and diseases ready to muck everything up.
Emma Lookabaugh, a technical service rep for BASF, spoke about four basic things to focus on when getting the jump on nursery diseases at the most recent Cultivate event. While some may seem like common sense, remember that repetition produces results.
1. Focus on the scene. In your nursery environment, most of your plants are disease-free. That’s a good place to start. You should always be on patrol, though. Be on the lookout for anything suspicious – leaf spots, blights, Phytophthora, diebacks, cankers, etc. Examine the lower leaves first – if a problem there is left unchecked, it can lead to full defoliation. And always isolate incoming materials and scout them thoroughly before placing them with everything else.
“If you pick good products, they will deal with most fungal problems,” Lookabaugh said. Those most often present with purple or reddish margins as the color in the center fades. Tiny black spots are the fungi’s fruiting bodies.
Be aware that disease can also look different on different cultivars though.
Lookabaugh said cankers most often form due to environmental stresses. Plants usually succumb to other diseases, not cankers.
Root diseases will present with stunting, then yellowing, and then severe wilting issues on one side of the plant. “Plants can limp along for a while with half of their roots dead,” she said.
When focusing on the entire scene, remember the disease triangle: host, pathogen and environment. If you can control even one side of the triangle, diseases will have a harder time getting established.
2. Protect the plants. “The easiest way to break the triangle is to use effective fungicides and planting resistant cultivars when possible,” Lookabaugh said.
She also reminded growers that “protective fungicides aren’t medicine – they are armor.”
There are different kinds of fungicides: persistence (high affinity with a waxy layer); protective (redistribution by superficial vapor movement, then re-deposition); preventative (with translaminar activity). Mesostemic fungicides provide a barrier to pathogen infection, prevent spores from germinating and don’t allow fungi to penetrate turf tissue.
As any fungicide moves though a plant, though, its strength does decline.
Be able to admit when a plant is too far gone. “Fungicides don’t wake the dead,” Lookabaugh joked.
When you see a foliar disease, use a spray; for root and crown diseases, use a drench. Very few systemic chemicals move both up and down a plant.
Lookabaugh told growers to pick their favorite 7+11 pesticide combination. Start with a foundational combination and rotate in specialists as needed for specific diseases.
3. Remember that the clock is ticking. “You want to prevent before you have to treat,” Lookabaugh stated. “Remember that preventative is better than curative.”
Timing is crucial both before and after disease is discovered. Heavy disease pressures mean tighter spray intervals.
Proper timing of fertility and irrigation management are important too. They, along with safe plant spacing, are things growers can manipulate for healthier plants.
4. Clean up the streets. There’s a reason people say “cleanliness is next to godliness.” Lookabaugh reiterated that good sanitation will save you the most time and money in the long run.
Take the time to clean everything in the nursery properly. If you do find disease, don’t recirculate water, reuse potting media or transplant into dirty or diseased pots. Be sure to get rid of cull piles – either in trash bags or by burning them. And don’t be afraid to get rid of diseased material. Make the decision as soon as you can to save more plants.
If you want to learn more, Lookabaugh mentioned there are resources at betterplants.basf.com.
by Courtney Llewellyn
