Storms: Planning for more than just your chips

 

It may seem early to start thinking about downy mildew or some of those other nasty fungal pathogens that are sure to be coming our way soon. However, as storm systems make their way up the Eastern Seaboard they usually bring spores with them from diseased fields all along the coast. In addition to transporting spores to our province they usually provide ideal conditions for fungi to colonize plants as these systems often bring with them sustained wet, cool, and humid conditions.

Downy mildew was positively identified in New Jersey last week and while it doesn’t look like storm Bret and the newly developing storm Cindy will be tracking over Nova Scotia anymore, it’s important to monitor systems coming up the Eastern Seaboard to correctly time preventative fungicide sprays and other IPM techniques such as trapping and scouting for new pests and ensuring physical barriers such as insect netting are in place as needed.

Over the last 2 years downy mildew has become a serious problem for cucurbit growers here as it is devastating when it gets a foothold in your field. Over the last 2 years both of the first confirmed occurrences in Nova Scotia happened in August, however, we need to be prepared for earlier occurrences as it is only one storm system away once it is detected along the eastern U.S coast. Along with fungal spores, these systems can bring with them novel insect pests to be mindful of as well.

Please reach out to your commodity support specialists if you have any disease or pest concerns!

Click here for excellent information on effective disease management, fundamentals of fungicides, herbicides and using weather stations for decision making on your farm

here for more information on downy mildew in Nova Scotia

Tim

Cucurbit Downy Mildew was detected in New Jersey on June 13th, 2023

The first incidence of Cucurbit Downy Mildew was detected in New Jersey, United States on June 13th, 2023. Previously (in 2021 and 2022) Clade II has been detected in Nova Scotia, in the Annapolis Valley region, which predominantly infects cucumbers and cantaloupes. Clade I, which affects watermelon, pumpkin, squash, and zucchini has not yet been detected, but monitoring should still be undertaken in these crops on the chance that it does make an appearance.

It is important that growers remain vigilant and scout their fields regularly for this disease, as spores may be blown into the province by storm systems in the United States. We are not recommending protectant fungicides at this point in time, but strongly recommend weekly scouting for disease.  Downy mildew may be identified initially as water-soaked lesions that appear on the top side of the leaf, which may first appear on any region of the canopy. The most ideal time to identify these lesions are during or right after a heavy dew. The centre of the lesion initially appears chlorotic or yellow before eventually the tissue dies, becoming brown or necrotic (Fig 1 and 2). This disease is very fast spreading, the lesions will continue to spread across the canopy, and quickly kill the entire plant if left unchecked.  When conditions are humid, a “downy growth” may be observed on the underside of the initial water-soaked lesions. These symptoms may first appear before lesions on the upper leaf. This growth is particularly apparent in the morning, after a period of wet weather or dew formation.

Growers must stay vigilant, scout often, and report any positive findings they may see.

 

Figure 1: Chlorotic lesions associated with downy mildew infection on cucurbits.

Figure 2: Necrotic lesions associated with downy mildew infection on cucurbits.

If you suspect downy mildew in your field, please contact Dustin MacLean, the Field Plant Pathologist at dustinmaclean@perennia.ca or 902 324-9623.

 

 

Posted by Dustin Maclean, Horticulturalist and Field Plant Pathologist with Perennia

First Occurrence of Downy Mildew in Nova Scotia in 2022

 

Downy mildew (DM) was diagnosed on cucumber Monday, August 29^th, 2022, in Annapolis County, Nova Scotia by both visual inspection and spore identification using microscopy. The strain of DM that affects cucumber also affects cantaloupe. At this time, cucurbit crops other than cucumber and cantaloupe are not at risk.

Figure 1: Downy mildew infected cucumbers

Growers should now add DM-targeted fungicides to cucumber and cantaloupe spray programs. Rotate between FRAC groups of targeted materials and combine targeted materials with broad-spectrum, preventative materials to prevent resistance development.

Where possible, tank mix Zampro (maximum 3 applications per year, 1 day PHI) or Orondis Ultra (maximum 4 applications per year, 0 day PHI) with chlorothalonil (maximum 2 applications per year, 2 day PHI) or mancozeb (maximum 3 applications per year, 14 day PHI). Never make back-to-back applications of the same product or products from the same chemical family. Follow a 5 to 7-day application interval, and rotation of the three products can be repeated as necessary.

Downy mildew can often be confused with angular leaf spot, bacterial leaf spot and Alternaria leaf spot. Downy mildew can be identified by dark sporangia growing on the underside of the leaf.

If you would like confirmation that downy mildew is present in your crop you can contact Dustin MacLean, Perennia Field Plant Pathologist at dustinmaclean@perennia.ca or call 1 902 324-9623

Figure 2: Sporangia developing on underside of cucumber leaf.

Table 1. Downy mildew multi-site, broad spectrum fungicides

Common name (FRAC group)	Trade Names	Rate per hectare (Rate per Acre)	PHI (days)	Re-entry interval	Max applications
mancozeb (M03)	Dithane Rainsheild, Penncozeb 75DF Raincoat Manzate Pro-Stick	3.25 kg (1.3 kg)	14	12 hours	3*
chlorothalonil (M05)	Bravo ZN Echo	4.8 L (1.9 L)	2	12 hours	2

 Table 2. Downy mildew specific fungicides

Common name (FRAC group)	Trade Name	Rate per hectare (Rate per Acre)	PHI (days)	Re-entry interval	Max applications
amectotradin (45) + dimethomorph (40)*	Zampro	0.8-1 L	1	1 day for hand harvesting, pruning or thinning , 12 hours for other activities	3
oxathiapiprolin (49) + mandipropamid (40)*	Orondis Ultra	0.4-0.6 L	0	12 hours	4

 

 

Farming in a Humid Year, Part of Perennia’s “Getting into the Weeds” Seminar Series

 

We are excited to announce our virtual seminar series Farming in a Humid Year, part of our annual Getting Into the Weeds series.  This year we are excited to host five online sessions to discuss several aspects of farm management in a humid year.  For more details, please click on the links below.  Please join us as we take a deep dive into agriculture production targeting moving the industry forward!

Pesticide points and CCA CEU Points will be available!

 
November 23, 12:00-1:00
Paul Hildebrand: Understanding the Infection Cycle on Your Farm: Targeting Effective Disease Management.

November 30, 12:00-1:00
Sajid Rehman: A Disease Summary of 2021 – What Did We Learn?

 
January 12, 12:00-1:00
Jennifer Foster and Katie Goldenhar: Fundamentals of Fungicides.

 
February 3, 12:00-1:00
Peter Sikkema: Why Herbicides Fail: Targeting Effective Herbicide Application.

 
TBD
Dan Olmstead: How Weather Station Decision Support Tools Can Affect You and Your Farm.
Stay tuned for more updates: https://www.perennia.ca/learning/online/

Garlic harvesting time

Hard neck garlic harvest in Nova Scotia typically happens the first week of August, although with how hot this summer has been (Table 1), some varieties are a bit ahead of schedule.

Table 1. Degree day accumulations as of July 26, 2021.  All data are taken from the Kentville weather station, based on a start date of March 1, and calculated using the single sine method.

 

Fig. 1. This garlic from mid-July, isn't quite ready to
harvest. Note how the wrapper leaves aren't yet snug
around the cloves.

I have blogged about garlic harvest timing in the past, and if you haven't come across it before, I strongly recommend giving it a read!  The number of green leaves left is a good tell, but if your garlic is super healthy, or super sick, it might not be the best barometer (Fig. 1).  You can find the blog post by typing "garlic" into the search bar on the right of the NS Vegetable Blog, or for direct access, click here.  

By mid-August my car usually smells of garlic from all the samples of unhappy garlic I've collected from growers.  This is often the result of poor post-harvest management.  August in Nova Scotia, when growers are trying to cure their garlic, is often a muggy month, providing poor drying conditions. 

Fig. 2. Relative humidity and temperature.

You NEED good air circulation and ideally low relative humidity (less than 70%) in your curing space otherwise you run the risk of disease running rampant.  If your garlic is taking more than three weeks to cure, it is likely your relative humidity is too high.  There are cheap sensors available from Canadian Tire or Amazon to measure relative humidity and temperature.  If you are serious about growing garlic, I strongly recommend you get one.  Some of the nicer sensors even upload it to a web portal (Fig. 2) so you can check on it from the comfort of the couch. Move the sensor around your drying space to see if you can find any "dead" space with low air movement and higher relative humidity.  Those are the areas where disease is most likely to rear its ugly head.  It is best to try and move some fans to around to get rid of this dead space.

Fig. 3. Unhappy garlic - Penicillium (blue) and
Rhizopus stolonifer (white and black fungus). 

Did you know you could submit samples to 
Perennia's Plant Health Lab?  This service
is often free for registered farms.  Reach out to
me, Rosalie Gillis-Madden, if you have a vegetable
sample you want to submit to the Plant Health Lab.

It shouldn't need to be said that diseased garlic should not be used for seed.  Advanced growers with smaller plantings sometimes earmark particularly healthy plants in the field before harvest as candidates for seed stock.    To read more about garlic storage, post-harvest diseases, and planting stock considerations, check out Perennia's factsheet.

Fig. 4. Garlic storage, post-harvest
diseases, and planting stock considerations
fact sheet.

Upcoming Perennia events

The Dirt on Dirt: Sustainable Soils on the South Shore  
Please join Amy Sangster, Perennia Soils Specialist, Rosalie Gillis-Madden, Perennia Vegetable Specialist, and Brian MacCulloch, NSDA Agriculture Resource Coordinator, for an afternoon focusing on soils, potting mixes, and transplant health.

Tuesday March 27, 2018 1:00 - 3:00 PM
Provincial Building Boardroom, 312 Green St. Lunenburg, NS

More details can be found on the Facebook event here.

Registration is required, please contact Gail Walsh 1-877-710-5210 (toll-free) or 902-678-7722 to register by March 23, 2018.

Pest Management in the Hopyard

There are many factors to consider when managing pests in a hopyard: life-cycle of the organism, good Integrated Pest Management (IPM) techniques, mode of action and efficacy of the products, and pesticide application efficiency. Pesticide Points will be available.

April 5th from 2-4 pm

This workshop is designed for growers with existing hopyards and will be informative for organic, conventional, and spray-free growers.

A session will be held in-person at the Perennia offices at the Kentville Research Station (32 Main Street, Kentville, NS) OR you can join remotely from

• The Truro Perennia offices (199 Dr Bernie MacDonald Drive, Bible Hill, NS)

• The Antigonish NSDA offices (190 Beechhill Road, Antigonish, NS)

More details can be found on the Facebook event here. Please contact Gail Walsh 1-877-710-5210 (toll-free) or gwalsh@perennia.ca to register by April 3, 2018, so we can be sure to accommodate numbers.

Biosecurity is important in horticulture crops too!

Biosecurity, often thought of as a livestock issue, is important in horticulture crops too.  The old adage "an ounce of prevention is worth a pound of cure" is very true for horticulture biosecurity risks, especially since many issues don't have viable solutions.  Equipment can carry soil-borne pests like clubroot, Verticillium wilt, and nematodes from field to field.  The more soil that gets transported between sites, the higher the risk of infection from these soil-borne pests.  Diseases such as downy mildew, late blight, and angular leaf spot can be inadvertently carried on clothes, boots, and gloves.  Difficult to control weeds such as yellow nutsedge can also be carried from field to field on equipment.

Clubroot can be transmitted on equipment, boots, and eroding soil

Important biosecurity management steps are first to make sure that these diseases and pests don't come on to the farm.  If you know you already have problem areas, takes steps to manage and contain them so that it doesn't spread to the rest of your fields.  Manage your culls and plant certified disease-free seeds and root stock.

To read more about biosecurity risks and how to manage them, check out Perennia's Horticulture Biosecurity Fact Sheet.

Sprayer Efficacy Workshop - Location

The Sprayer Efficacy Workshop will take place on Thursday, July 20, 2017 from 1:00 - 3:00 pm.  The approximate street address is 9780 NS-201, Wilmot, NS.  Keep your eyes peeled for Perennia signs!
 


If you contact Gail Walsh 1-877-710-5210 (toll-free) she will email you a map.


Perennia IPM Specialist Peter Burgess and Vegetable Specialist Rosalie Madden will discuss nozzle selection, canopy penetration, and the importance of water volume!  Pesticide points available.

Thursday, July 20, 2017 

Spurr Brothers Farms, Melvern Square 

1:00 p.m. - 3:00 p.m.

Sprayer Efficacy Workshop

Please join Perennia Integrated Pest Management Specialist Peter Burgess and Vegetable Specialist Rosalie Madden for a discussion about sprayer efficacy.

We will discuss nozzle selection, canopy penetration, and the importance of water volume!  Pesticide points available.

Thursday, July 20, 2017 

Spurr Brothers Farms, Melvern Square 

1:00 p.m. - 3:00 p.m.

Please contact Gail Walsh 1-877-710-5210 (toll-free) or gwalsh@perennia.ca to register by July 17, 2017.

Be sure to give Gail your e-mail address as we will send out a map of the field locations the day before the workshop.

 

Cucumber beetles are here

Stripped cucumber beetle, illustration by Jessica MacDonald

Striped cucumber beetles have made their annual debut in the Annapolis Valley.  These pests are problematic in many ways.  Feeding damage can stunt plants, and when flowers are predated, it can reduce fruit set and yield.  Cucumber beetles also vector bacterial wilt.  Scarring on fruit by adult beetles reduce the marketability of the crop. 

Newly emerging cucurbit plants are particularly susceptible to stunting and bacterial wilt, while older plants can withstand up to 25% defoliation.  Early season control is essential with this pest, and it is important to scout your fields regularly. 

For more information on cucumber beetle biology, beneficial insects, and organic management, check out Managing Cucumber Beetles in Organic Farming Systems on eXtension.
 
Please click here for Perennia's Pest Management Guides for Cucumbers and for Melons.  For Perennia's Pest Management Guides for Pumpkin and Squash, please click here.  Insect netting can also be an effective control option for this pest, but netting must be removed at flowering for pollination to occur.

Carrot Pest Activity

Ontario has a Carrot Pest Activity Calendar, which is a great resource to help you predict when pests might start to become a problem. You can find the full calendar here: https://onvegetables.files.wordpress.com/2017/04/carrot-pest-activity-calendar.pdf  As the calendar is based on Ontario dates, there will be slight variation for Nova Scotia conditions, but it's well worth a read! 

Hurricane Arthur Damaged Vegetable Crops

Hurricane Arthur left considerable damage to vegetable crops.  Injury to the crops would depend on the intensity of the wind in the area.  Severe wind caused leaf defoliation, leaf tearing and shredding, stem breakage, stem bruising and wounding.

Effects of Arthur on vegetable crops and recovery of the crops will depend on a number of factors including the type of vegetable, stage of growth, weather conditions immediately after the storm, and prevalence of disease organisms.  Growers should begin a fungicide program immediately to prevent any disease spread as continued hot weather poses a risk of increasing disease incidence.

Defoliation reduces leaf area and plants will need to grow new leaves from buds (for vegetables such as vine crops where this is possible).  It may take from a week up to several weeks for crops to regrow the leaf area lost.  This may cause delays in maturity and lower yields.  The more mature crops were, the heavier the yield losses that can be expected.  

In order to speed up plant recovery, additional nutrients (mainly nitrogen) will be needed for plants to recover.

Leaf Curl - A celery disease

Leaf Curl causes malformed cupped-leaves, downward curled leaves, the development of lesions on the stalks and eventually twisting of the stalks.  The disease symptoms are similar to symptoms of several other diseases of celery.  Infected celery plants are not marketable.  (Clicking on the picture below will enlarge it.)

An OMAFRA vegetable blog suggests that fungicides with action against early and late blight of celery may also have action against leaf curl.  For information on fungicides registered for celery in Nova Scotia see the Guide to Pest Management in Celery beginning on page 10.

Michigan State University Extension has published an very informative article, Celery Anthracnose: a newly identified fungal disease of celery, which includes a number of pictures and frequently asked questions.

Early Blight (Alternaria solani) of Potato

Primary damage to potatoes by early blight is attributed to premature defoliation of the potato plants, which results in tuber yield reduction.  Initial infection occurs on older leaves with concentric dark brown spots.  Disease severity is highest when potato plants are injured, under stress or lack proper nutrition.

Please consult the 2014 Potato Crop Weed and Pest Control Guide for information on control options.