Hop Irrigation Watch, June 2018 Update

OMAFRA Hop Irrigation Logo

Over the last 14 days, dry conditions have persisted in South and Central Ontario with minimal precipitation other than isolated showers and thunderstorms in some regions.  Figure 1 shows the 14 day accumulated precipitation for Southern Ontario and Eastern Canada from AAFC’s Canadian Drought Monitor.

14 day accumulated precipitation
Figure 1: 14 day accumulated precipitation as of 14 June, 2018.

As we consider the previous 30 days, much of the southern part of the province is well below normal precipitation amounts for this time of year (Figure 2).

30 day percent of normal
Figure 2: 30 day percent of average as of 14 June, 2018.

With dry conditions continuing across much of the province, it is important to be continually monitoring precipitation amounts and frequency in your hop yard.


Water availability to hops is essential during the vegetative growth stages and inflorescence development through to cone maturity.   Studies have shown that supplemental irrigation can improve yield and quality of hops and may positively affect alpha acid concentrations. Most recommendations suggest 7.5 L of water per plant per day (~2 U.S. gal/plant/day) is adequate for plant growth, however , some more recent information on Evapotranspiration (ET) rates of hops suggest the plant may require even more water, up  to 19 L/plant/day (~5 U.S. gal/plant/day) for optimal plant growth.  Always remember to include rainfall amounts when calculating how much supplemental irrigation should be applied.

The OMAFRA FactSheet ‘Monitoring Soil Moisture to Improve Irrigation Decisions‘ provides good information on irrigation practices and the tools available for monitoring soil moisture.  It is available online in HTML format or you can request a hard copy from Service Ontario.

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Hop Leaf Stripping in Ontario

Growing_Hops_Ontario_Logo_5 with shading

Leaf stripping (removing lower leaves and laterals; Figure 1) to increase air flow is a common cultural practice to manage hops downy mildew (P. humuli). Leaf stripping is performed earlier in Ontario than in other growing regions due to a shorter growing season and earlier occurrence of downy mildew.

Leaf stripping trial 2015







Figure 1: Leaf stripping (removal of lower leaves and laterals) trial on cv. Nugget at the Simcoe Research Station, Norfolk County, in 2015.

With a late start to the 2018 growing season, some cultural practices were either delayed or not performed this spring. However, with above normal temperatures in the latter part of May, many hop cultivars have responded with vigorous growth. Early and mid-season cultivars which were not pruned this spring are now reaching the point for leaf stripping to begin (if you haven’t started already). The preferred time to strip both mechanically or chemically is when the plants have reached the top wire of the trellis, however, if conditions are favourable for downy mildew (i.e. wet, humid weather), mechanical stripping should begin when the plants are at least 3 m (10′) tall. Chemical stripping (basal foliage removal) should always be performed according to the product label, which is when the bine has barked to withstand chemical application, typically once the hops reach the top wire. For more information on products registered in Canada on hops for basal foliage removal, including plant growth stage, application rates and volumes, please refer to the ‘Broadleaf Weeds, Suckers’ section of the Hops Pesticide List, 2017 on this blog.

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Lavender Crop Update – June 1, 2018

Now that lavender plants have “greened” up, it is obvious that this was a very damaging winter for lavender. Generally young plants, plants in sheltered areas, plants under row cover and hardier cultivars (i.e. ‘Folgate’) have performed better, but damage is present on most plants.

Angustifolia cultivars with top damage generally have new shoots growing from the base. Removing the dead growth above these new shoots can get more light to them and result in faster recovery of the plants. Mowing is an option, but rotary mowers should be avoided because they cause too much damage to the remaining branches, which could then be an entry way for diseases to get into the plant. These plants will have a small bloom this year, but could be back to a productive plant next year if given proper irrigation and fertility this year. If the root system is still intact, the plant can grow much faster than a newly planted plant, so there is no need to replant. If there is no green visible anywhere on the plant now, then the plant is dead and will need to be replaced. Continue reading

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Sampling for Plant Parasitic Nematodes in Ginseng

Reports of nematode damage on ginseng seem to be increasing lately. As I wrote on this blog last year, some of the damage thought to be nematode damage is actually due to other causes. When there have been reports of damage, in most cases the grower never took a nematode sample, so whether plant parasitic nematodes were actually present in the field and at what levels are unknown. Given the differences in fumigants in their ability to control nematodes in the soil, it is very important to know before fumigation whether nematodes are a problem on a site. Metam sodium products are known to control plant parasitic nematodes better than chloropicrin, although this depends on whether the proper application procedures are followed. It makes the most sense to sample for nematodes even before choosing the land for ginseng production, because some sites may not be suitable for ginseng production due to excessively high nematode populations. Continue reading

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Ginseng Crop Update – June 1, 2018

With the hot, humid weather over the past few days, Alternaria is reportedly showing up in many older gardens. Most of the damage is within the canopy and along the stems. This is where it is most difficult to reach with fungicide sprays.  A combination of timely sprays, a rotation of effective products and good spray coverage are necessary to keep Alternaria under control. Studies lead by OMAFRA’s Sprayer Technology Specialist Dr. Jason Deveau have shown the importance of drop nozzles down each row for achieving good covered of the stems within a dense canopy. Consult the following two resources for more information on achieving the best spray coverage.

A Comparison of Sprayer Technology in Ginseng

The Perfect Sprayer Boom for Ginseng?

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2018 Downy Mildew Control Strategy for Cucumber Crops — ONvegetables

Specialty cucurbit growers may be interested in the following InfoSheet on downy mildew control strategies in cucumber crops written by Elaine Roddy, OMAFRA Vegetable Crops Specialist.  Note that not all products registered on cucumber for downy mildew are registered on all specialty cucurbits (e.g. bitter melon, bottle gourd, fuzzy melon, winter melon, mousemelon).  Please read the label prior to product application to ensure it is registered on your specialty cucurbit species.

2018 Downy Mildew Control Strategy for Cucumber Crops

via 2018 Downy Mildew Control Strategy for Cucumber Crops — ONvegetables

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Ginseng Crop Update – May 25, 2018

Although ginseng emergence was slow this year, weather conditions have been ideal over the past few weeks for emergence and development. However, it is important keep an eye out for foliar Phytophthora, which usually shows up around this time each year. Earlier this week there were extended periods of leaf wetness that may have allowed enough time for Phytophthora infection of tops. If more rains end up coming this weekend, especially heavy downpours in thunderstorms, the risk will be high for infection again. Continue reading

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