Minimizing injury from copper fungicides

 

Copper damage in crucifers, lettuce and strawberry’s results in small black spots on the plants leaves. This happens when the concentration of ionic copper in the plants surpasses the plants manageable level. Copper damage is typically instantaneous with smaller damage spots. Some factors can increase the likelihood of copper damage by upping the amount of available copper on plant foliage leading to increased copper uptake. These factors include the pH of the spray solution, as lower pH values make Copper more soluble. Other factors are particle size, the frequency of application and rate of solution, water availability to the plant (more rain higher solubility of copper), age of plant tissues, product age, copper type, and finally metallic concentration of the product. All these factors play a role in the solubility of copper and the development of copper-based injuries on crop foliage. Optimizing these factors to minimize can therefore prevent copper-based injuries on crops.

By Jordan Etheridge

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

 

 

Product Registration Changes in Vegetables!

Recently PRMA (Pest Management Regulatory Agency) has approved several IMPORTANT minor use label expansions in vegetable production. Minor use label expansions of pest control products are considered on active ingredient(s) currently registered in Canada, which are expanded for additional end uses.  Below is a table outlining some of the key information about these products and their end uses (add table directly below this paragraph).  Before integrating these products into your current pest management program, please review the label thoroughly and if needed, consult with your favourite agronomist.  The Health Canada label search tool has the most accurate and up-to-date labels, and can be found here.

 

Through the emergency use registration process Ontario, Quebec, Nova Scotia, Prince Edward Island, and Newfoundland and Labrador were successful in obtaining SWITCH®62.5 WG (cyprodinil (group 9) and fludioxonil (group12)) for use has been approved PMRA for the suppression of Alternaria leaf blight (Alternaria brassicicola) on Brussels sprouts, broccoli, and cauliflower.  Being an emergency use registration, this use pattern is only permitted from July 8^th, 2022, to July 7^th, 2023, however a user requested minor use label expansion for this use of SWITCH®62.5 WG has been submitted and will hopefully be approved for the 2023 growing season.  

For more information on these products, consult the label or contact your local agronomist.

Written by Jenna Bekkers, Perennia Agricultural Research Technician

Be on the Lookout for Cucurbit Downy Mildew in Nova Scotia

Cucurbit downy mildew was detected in Nova Scotia for the first time in 2021 in Annapolis, Kings, and Hants Counties. It has not yet been found in Nova Scotia in 2022, but has been reported in New Jersey, USA on June 11^th, 2022. Currently, only Clade II has been discovered in Nova Scotia, 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

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/

Updates on Cucurbit downy mildew

Monday, August 30th, 2021 downy mildew was found in King's County.  Please read the original blog post here.  Downy mildew that infects Cucurbits is specific to Cucurbits - it won't infect onions, grapes, hops, lettuce, spinach, basil, etc.

There is a great Cucurbit Downy Mildew Diagnostic Key, which might help you determine if you have downy in your field.  Please do not hesitate to reach out if you need support in identification and you are a registered farm in Nova Scotia.

So far, downy mildew has only been confirmed here on cucumbers.  The Nova Scotia Vegetable Blog will be updated if that changes.  There are two different host-specific clades of downy mildew.  Clade I mostly infects watermelon, pumpkin, squash, and zucchini.  Clade II mostly infects cucumbers and cantaloupe.  It is possible that we currently only have Clade I in Nova Scotia.  However, there is a storm system blowing in on Thursday/Friday that will certainly bring downy conducive conditions (i.e. prolonged leaf wetness), and perhaps more infections spores of either Clade I or Clade II.  

Cucumber and melon growers should apply protective fungicides as outlined in yesterday's blog post.  Pumpkin, squash, zucchini, and watermelon growers can take a gamble - either apply a protectant as previously mentioned; do nothing and hope there isn't downy that will infect the pumpkin/squash subset; or harvest early.  For growers that do not have established drive rows in their winter squash and pumpkins - especially if they are close to harvest - it may be worth the risk to wait see and thereby avoiding driving over crop to make a fungicide application.  Harvesting early is a good option if the crop is mature and you have curing facilities, especially in light of the forecasted precipitation coming our way on Thursday/Friday.  Downy mildew does not affect fruit, however in the case of cantaloupes, the fruit will be less sweet.  

New pesticide registrations

Agri-Réseau is a resource available through The Centre de référence en agriculture et agroalimentaire du Québec (CRAAQ).  Every month, they publish a list of new phytoprotection registrations.  At Perennia, we are fortunate to have Mélanie Leclerc as part of our staff, and she has translated the March list of new pesticide registrations for Fruit Trees, Field Crops, Vegetables, Greenhouse, Berries, Ornamental, and "Other" (hops, hemp, quinoa, and basil), which can be found here.

From the Vegetable side, the main excitement is a few more weed control options in asparagus, Brassicas, and shallots, and some new disease management options in asparagus, kohlrabi, Brassica leafy greens, and bulb vegetables (Group 3-07A and 3-07B, so bulb onions, garlic, shallots, green onions, leeks, etc.)

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.

Alliette re-evaluation

Alliette (fosetyl-aluminum) has recently undergone re-evaluation by the Pest Management Regulatory Agency.  Alliette is a systemic fungicide used manage a wide variety of diseases in various crops.  In vegetable production, it is used to control downy mildew in onions, lettuce, spinach, rutabaga, and many Brassicas, as well as white rust in spinach, purple blotch in onions, and damping-off in some greenhouse transplants.

There are a few new measures that have been proposed that may be relevant to Nova Scotia vegetable production.  Always follow the label.  Labels for all pesticides registered in Canada can be found here.

To protect workers entering treated sites, the following measures are proposed:

• Increase REIs for Brassica leafy vegetables (currently 12 hours), onions (currently 12 hours), spinach (currently 12 hours), as well as apples, blackberries, highbush blueberries, red/black raspberries, grapes, and ornamental plants.
• Establish a minimum 12-hour REI for other crops where appropriate.

To protect mixers, loaders and applicators, the following measures are proposed:

• Prohibit the use of fogging equipment (handheld or automated) or handheld mistblowers.
• Wear a chemical-resistant hat for airblast applications.

To read the full decision, please click here. There is a 90-day public consultation period if you wish to make your voice heard. 

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.

Downy mildew in lettuce

Downy mildew was found in a lettuce field in the Valley this week by Erika Bent (APM Agricultural Pest Monitoring Cons. Ltd.).  We don't always see lettuce downy mildew (Bremia lactucae Regel), but it can be very destructive. Spores are spread via splashing water or wind.  Air currents can carry spores several kilometers.  Cool temperatures (between 15' and 21' Celsius) are conducive to disease development, especially under wet conditions.  This includes heavy dew set in the mornings and overhead irrigation. 

Infection usually starts in the older leaves and travels inward.  Pale green or yellow areas will become apparent on the upper surface of the leaves, often having an angular appearance, with sporulation occurring on the underside.  This infection can spread very quickly, especially under favourable growth conditions, so be sure to check your fields often!

Fields that have been recently harvested are ideal locations for disease buildup to get out of hand, so be sure to plow down lettuce residue.

There are numerous fungicide options, which can be found on the Perennia Lettuce Management Schedule. Downy mildew can build up resistance to pesticide group modes of action very quickly, so be sure to rotate between pesticide groups at every application. While there are varieties that have been bred to be resistant to downy mildew, due to the quickly evolving nature of this disease, varieties may not be resistant to all strains of downy mildew.