Harvest 2017 is in the books, and there’s a nip in the air that hints that the fall equinox is not far away. Take a deep breath and relax as the to do list around the hop yard grows small in preparation for winter.
Post Harvest Agronomic Practice Recommendations
Bines, 2nd year and older, should’ve been cut back to 2-3 feet above the ground at harvest. Following the first hard frost and at least 4-6 weeks after harvest, bines can be cut to a few inches above the soil. For 1st year plants and older, aerial shoots should be removed, especially if disease pressure was significant in your yard. First year bines can remain through winter or cut back with everything post frost. Plant material should be buried, burned or if disease was not present on bines, they may be fully composted.
Use this time to get control of weeds present in your hop yard. Herbicides such as Volunteer for grasses and Aim for broad-leaf weeds. Weeds provide another shelter for fungal structures to overwinter so get a head start on next season by removing them!
If your hop yard’s soil is primarily clay, you may want to take time in the fall to hill your plants. It’s also a great time to incorporate compost to replace some of the nutrients lost when hops are harvested. Soil along either side of the plants may be lightly tilled, incorporated with composted, then piled a few inches on top of the crowns. This may help to reduce chances of winter kill and kill off downy spores present in the soil. “Hilling” is a great way to improve drainage for the following season as well.
Once harvest is complete, drip irrigation should be backed off to a couple times a week at most. Growers should keep the yard on the dryer side, especially as downy mildew spores require moist soils to survive. You may find that rainfall and cooler temperatures provide sufficient moisture.
Post Harvest Pest and Disease Management
For effective management of pests and diseases all season long including post harvest, we have to look at the individual life cycles of each pest or disease. We’ll take a closer look at some of the problems we’ve had across the state:
Downy mildew. The pathogen causing downy mildew survives in the form of mycelium in plant debris and in the crown of hop plants, emerging in the spring on infected flag shoots. In the spring, mycelium develop spore bearing structures which release zoospores. Zoospores travel via the wind or rain drops, and can infect new stems, leaves and flowers, over and over throughout the season. Mild, rainy weather in the spring makes for the ideal downy mildew infection.
Since the pathogen can be harbored in debris, all debris should be removed, and buried or burned. Because the pathogen can overwinter in the crown as well, a systemic fungicide that will move down the plant may be applied. Aliette or a phosphite based fungicide are options. With little leaf tissue for application, and little research to support these applications, a better bet for those with downy infections in the 2017 growing season should use the winter to develop an aggressive protective program for the 2018 season.
Potato leaf hoppers. Potato leaf hoppers overwinter in the southeast region of the United States. Their migration north and west occurs in spring or summer storms. For this reason, there is no management needed post harvest for potato leaf hoppers.
Aphids. Aphids breed and over winter in the bark of Prunus species, such as apples, apricots or peaches. As the weather cools, aphids will mate and move back to a Prunus species to lay eggs and overwinter. No post harvest management is recommended.
Spider mites. The advantage in treating spider mites post harvest is that when hop bines are removed at harvest, most of the spider mites are removed at the same time since they’re removed fairly early in the season. Some mites will remain in plant debris or in the trellis posts for the winter. Post harvest treatments are not generally recommended unless infestations reached devastating levels. Scout your yard, counting mites per leaf. If 10+ mites are present on average per leaf, a post harvest miticide application is recommended.
Take a moment to reflect on the season, what you did that worked well, and what you will do better next year. I hope you will reap the benefits of your labors this season with a fresh harvest ale in your near future!