Tortoise beetles on sweet potatoes

Tuesday, July 9, 2019

These fascinating beetles are a minor pest of sweet potatoes.  Early in the season, damage can look quite alarming, but rarely hits yield-limiting or economically damaging levels.  The Golden Tortoise Beetle (Charidotella bicolor) and the Mottled Tortoise Beetle (Deloyala guttata) will often come in on slips.  Areas that are protected from predators (i.e. under row cover) tend to show greater damage.  In Nova Scotia, there is typically only one generation per year and they do not overwinter.  Growers typically start noticing feeding damage in early July.  Not to get wildly dorky, but the adults look like if C3PO and R2D2 had a baby (Figure 1).  Adults are 5 – 7 mm in length and are metallic gold or orange, but can shift to a redder colour when disturbed.

Figure 1. Adult tortoise beetles.

You may also notice golden tortoise beetle larvae in your sweet potatoes (Figures 2, 3).  Larvae yellowish to reddish-brown and are broad and flat with spikes.  They have an anal fork and will use it to shovel old skin and fecal matter onto the spines on their back.  This creates a "poop shield", which, unsurprisingly, deters predation.

Figure 2. Tortoise beetle larvae with "poop shield".
Figure 3. Clearly an effective predation deterrent.
Both adults and larvae will feed on sweet potatoes and other members of the Convolvulaceae family, such as field bindweed and morning glory, causing irregular small- to medium-sized holes (Figure 4).  Tortoise beetles are a minor pest of sweet potatoes and chemical control is usually not warranted.  Sweet potatoes are a vigorous crop and will typically outgrow the damage (Figure 5).

Figure 4. Tortoise beetle damage, July 11, 2017.
Figure 5. Tortoise beetle damage in the same field on August 30th, 2017. 
Written in part by Cassidy Coombs, Perennia summer student.

Growing degree days and crop and pest development

Monday, July 8, 2019

I was talking to Michelle Cortens, Perennia's Tree Fruit Specialist, this morning and she mentioned something interesting...  By June 5th, we had achieved the status of ‘coldest spring in the last 20 years on record’. I'm sure none of you are surprised to hear that.  Many crops use a 5℃ Growing Degree Day model, while many insect pests use a 10℃ Growing Degree Day model.  

Graph courtesy of Orchard Outlook.  Click here to subscribe or read past issues.

We were pretty far behind in insect degree days by about 44-49% less than average.  By comparison, the plant development heat units were at about 21-28% of average.  Some growers may be noticing this in their fields - pests that you normally expect at, say the end of May/early June showed up later, and are continuing to cause problems longer than they normally would (i.e. flea beetle).

The good news is, now that we're starting to get some heat, Growing Degree Days are starting to look more like what you'd expect at this time of year.  We're still about 13% less plant development heat units (base 5℃) compared to the 5 year-average, and 17% less compared to the 10-year average as of July 2.  We have 25% less insect development heat units compared to the 5-year average (10℃ base), and 27% less compared to the 10-year average.

Graph courtesy of Orchard Outlook.  Click here to subscribe or read past issues.

Garlic scape removal

Sunday, June 30, 2019

If you haven’t signed up for it before, OMAFRA has a fantastic vegetable blog.  A couple of years ago, Travis Cranmer, OMAFRA’s Allium Specialist, wrote a great piece about the benefits of removing garlic scapes.

Figure 1. Yield and bulb weight in response to scape removal timing of
garlic cv. ‘Music’. (Zandstra, 2006)
John Zandstra did some research on scape removal and the influences it has on yield.  Scapes should be removed sooner rather than later to preserve yield and bulb size (Figure 1). The longer you leave the scapes growing in the field, the more energy the plant will divert to creating a flower and bulbils - to the detriment of bulb size and yield.

Figure 2. Influence of leaf removal on yields and bulb weights of
garlic cv ‘Music’. (Zandstra, 2000)
Best practices also suggest that the scapes should be removed by hand (Figure 2).  Using a sickle bar mower, or other mechanical means to remove the scape often damages leaves.  Damage to the leaves reduces the photosynthetic potential of the plant, resulting in less energy to be poured into bulb development.  In short, even a small percentage of leaf damage will reduce bulb weight and total yield so be careful when removing scapes!

Scape removal is also a good time to be on the lookout for leek moth damage in your crop. Leek moth is a new pest to Nova Scotia and has been found in Kings and Annapolis Counties.  Cornell has an excellent site devoted to providing further leek moth information.  If you grow garlic, leeks, or onions, I strongly suggest you make yourself familiar with this pest.

Leek moth damage on garlic, photo credit Amy Ivy, Cornell

Leek moth damage on garlic leaves, photo Amy Ivy, Cornell

Leek moth damage on garlic scapes, photo Scott Lewins, UVM

Pest Update - Leek Moth

Thursday, July 5, 2018

Perennia in association with NSDA and AAFC has been monitoring for leek moth across Nova Scotia since early May this year. Leek moth is an invasive insect pest from Europe that feeds on Allium species (onions, garlic, leeks,etc), and can cause significant damage to these crops. Previous to 2018, leek moth had been identified in Kings County in 2017. In 2016 gardeners reported damage on garlic which could have been due to leek moth but no specimens were ever recovered to verify these observations. In response to this a provincial leek moth monitoring project was established, to determine how widespread the pest is in Nova Scotia. As of this week we have confirmed leek moth in both Kings and Annapolis County. Currently we have not found the pest in large scale commercial fields, and all the leek moth samples we have identified have been from garlic. Leek moth favours garlic and leeks primarily; we are currently unsure of its effects in onion production.

Leek moth can be monitored using commercially available pheromone traps, which attract adult males. The adult leek moth is a small (5-7 mm in length) brown moth with a distinctive white triangle in middle of its wings when they are folded at rest. Additionally allium crops can be scouted for feeding damage from leek moth larvae. On alliums with flat leaves (garlics, leeks) the larvae feeds on the tops and inside of the leaves, as well as bores into the center of the plant leaving noticeable frass. In alliums with hollow leaves (onions, chives) the larvae will feed internally producing translucent areas on the leaf known as "windowing". The larvae will also occasionally bore into bulbs.

There are several chemical controls registered for leek moth in garlic, leeks, and onions that can be found in the Perennia's Garlic Management Schedule, Leek Management Schedule, and Onion Management Schedule. These pesticides are most effective when eggs are present and leek moth larvae are small, so monitoring is crucial to ensure proper timing of applications. Row cover is also an effective means of protecting allium crops against leek moth, without using chemical controls.

For additional information on leek moth identification and management please consult AAFC's An Integrated Approach to Management of Leek Moth . If you think you have leek moth please contact Matt Peill, horticultural specialist with Perennia (email:, cellphone: 902-300-4710).

Wishing you a great growing season

Friday, May 25, 2018

Today is my last day as the Vegetable Specialist at Perennia as I will be going on Maternity Leave, returning May 2019.  Please note that my cell phone (902-670-9655) will be inactive during this time.

Matt Peill
Matt Peill has been hired to cover the Vegetable portfolio in my absence, and will also be covering Small Fruit for Jennifer Haverstock when she goes on maternity leave at the end of June. 

You can either reach him in the Perennia Kentville office 902-678-7722 or his cell 902-300-4710 or by email.

Wishing you a great growing season,


New pesticide registrations

Monday, April 16, 2018

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.)

Upcoming Perennia events

Thursday, March 8, 2018

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 to register by April 3, 2018, so we can be sure to accommodate numbers.