What’s hoppening in Ontario – July, 2015

From Evan Elford, New Crops Development Specialist, OMAFRA and Melanie Filotas, Specialty Crops IPM Specialist

We’ve had a number of questions from hops growers lately.  Here’s an update on what’s going on in Ontario and some answers to the more common questions.

Acreage is expanding in Ontario this year as a result of both new growers establishing new hop yards and existing growers expanding current production.

Late season planting:

A few growers have called asking about late summer and early autumn plantings this season.  From other experiences in Eastern North America (within and outside of Ontario) it is becoming more apparent that late summer/early autumn plantings have poor overwintering capabilities and we see lots of winterkill in the following spring.  If possible, schedule plant/rhizome orders for spring or early summer planting in order to allow the hops enough time to establish themselves before winter by generating and translocating photosynthates back to the roots for productive growth in subsequent years.

Nutrition:

Optimizing nutrition and irrigation is very important in the establishment year to develop strong plants for future production.  These two aspects of production still appear to be a steep learning curve for many hop growers.  I can’t emphasize enough how important nutrition and irrigation are for optimal hop production.  Additionally, many nutrient deficiencies and pest issues can look similar in hops and cause confusion when trying making a diagnosis of symptoms, so it’s a good idea to develop your fertility and irrigation plan to minimize confusion if abnormal symptoms occur in your yard.

With heavy rains this season in parts of the province, there are some nutritional deficiencies, most likely nitrogen, being noted on plants.  We’ve also suspected some magnesium and boron deficiencies in a few yards/cultivars as well.  At this point in the season, plants have transitioned to reproductive mode from vegetative mode due to the change in photoperiod and therefore nutrient applications can cease.

Frost damage:

Some growers experienced damage on their hops this year due to a late spring frost on 22 May.  This is the second time we’ve recorded a severe late spring frost damaging hops in the last 3 years (previously recorded 24/25 May, 2013).  We have implemented a frost management trial to better understand the best cultural practices to optimize yield in years with this type of damage.  We hope to begin sharing preliminary results after this year’s harvest.  For more information on frost management options in hops, please refer to a previous blog post on the topic:  https://onspecialtycrops.wordpress.com/2013/05/27/growing-hops-in-ontario-frost-update-may-27-2013/

Crop Development:

As of the week of July 13th in the Southwestern Ontario region, cone development on early to mid-season hops, such as aroma cultivars Hallertauer and Centennial, dual purpose Nugget, and alpha cultivar Galena, have been observed.

Nugget cone development

Nugget cone development (July 16, 2015)

Centennial cone development

Centennial cone development (July 16, 2015)

Galena also has substantial lateral (sidearm) development this year.  Northern Brewer, traditionally an early to mid-season cultivar, is behind with very immature burr development.  Many mid and late-season cultivars, such as Cascade and CTZ, have good development of laterals, and at this point appear to have substantial burr set.

Cascade side arm and burr development

Cascade side arm and burr development

Downy Mildew

The frequent rains and humid weather that continue in many areas of the province are leading to persistent downy mildew pressure in some hop yards.  Problems have been worse in yards with widespread systemic infection, high disease pressure in past years or where fungicides could not be applied in advance of heavy rains.

For more information on identifying downy mildew in hops, refer to a previous post on this topic:

https://onspecialtycrops.wordpress.com/2014/06/03/identifying-downy-mildew-in-hops/

A detailed discussion on managing downy mildew in conventional hops can be found in this post:

https://onspecialtycrops.wordpress.com/2014/06/03/managing-hops-downy-mildew-in-ontario/

As we progress closer to harvest, hop growers need to pay close attention to pre-harvest intervals on pest control products, as these can be quite long for some hops products. In particular, the pre-harvest interval for Pristine (registered for suppression of downy mildew in hops) is 46 days.  Zampro and Acrobat 50 WP both have pre-harvest intervals of 7 days, however the re-entry interval for hand harvesting is 18 days.

Organic growers have gained an additional tool with the recent emergency use registration of Regalia Maxx biofungicide on hops in select provinces, including Ontario, until July 2016.  Prior to this, the only organic pest control product registered for use against downy mildew on hops was Copper 53W, which has a maximum of four applications permitted on hops per year.  Growers who have not already hit their maximum applications of copper may want to consider rotating between Copper 53W and Regalia Maxx as part of their management practices.

Fusarium canker

In recent weeks, we have seen some cases of bine death due to the fungus Fusarium. While the fungus has not yet been identified to species, symptoms are consistent with Fusarium  canker of hops.  Hops with Fusarium canker suddenly wilt and die, with the leaves remaining attached to the bines.

Dead bine with Fusarium.

These can appear similar to bines killed by wind or other mechanical damage, however the base of these bines will be swollen, then narrow near where they attach to the crown.

Hop fusarium swelling

Fusarium in hops appears to be favoured by mechanical damage and lots of moisture around the crown, so it may be related to the recent wet weather.  There are no fungicides registered to control Fusarium in hops, so management is primarily through cultural methods.  These include:  arching strings, ensuring drip irrigation is off the top of the crown to promote drying, minimizing wounding at the base of plants and avoiding acidifying ammonium-based fertilizers.  Hilling soil around the base of bines may help by promoting growth of healthy roots.

Japanese Beetles:

Japanese beetle populations are increasing in some yards, particularly in southwestern Ontario.  Japanese beetle are large, green and copper-coloured insects with tufts of white hairs along the wings.  They aggregate in large numbers and skeletonize the leaves of hops and a wide variety of other plants.

Japanese Beetle

Japanese Beetle

Because they are so large, scouting for Japanese beetles can be done by visual inspection. However, in many Ontario hop yards, Japanese beetles seem to concentrate much of their feeding on the upper third of the plant. When scouting hops, it’s a good idea to bring a pair binoculars and scan the top wire for signs of feeding.

Japanese beetle skeletonization of upper leaves along top wire.

Japanese beetle skeletonization of upper leaves along top wire.

There are no insecticides registered for Japanese beetle on hops in Ontario.  The neonicotinoid insecticde Admire (imidacloprid) is registered for control of hops aphid, and growers applying this products for aphids may see some reduction in populations of Japanese beetles.

Potato leafhoppers and two-spotted spider mite:

Potato leafhopper damage is significant in some yards, but populations remain low in many other areas.  Two-spotted spider mite populations remain low in many yards, however some leaf infestation has begun.   Mites can increase rapidly under hot, dry conditions, so growers should be scouting hop yards for bronzing due to mite feeding.  Mites, cast-skins and webbing can also be seen by inspecting leaf undersides with a hand lens.

Hop leaves affected by potato leafhopper exhibit a characteristic "hopperburn" starting at the leaf edge and moving inwards.

Hop leaves affected by potato leafhopper exhibit a characteristic “hopperburn” starting at the leaf edge and moving inwards.

Leafhopper nymph on the underside of a hop leaf.

Leafhopper nymph on the back of a hop leaf.

Bronzing mites

Bronzing of hop leaf due to mite feeding

There are no products registered for control of potato leafhopper on hops in Ontario.  Envidor 240 SC, Acramite 50 WS, Agri-Mek 1.9EC, Purespray Green Oil and the insecticidal soaps Opal, Neusodan Commercial and Kopa are registered on hops for control of mites, however growers should make note of pre-harvest intervals as some are quite long for hops.

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