T’is poinsettia sticking season once again, and the question always comes down to the same thing: do I use chemicals to control Bemisia whitefly and hope it works this year? Or do I switch to biological control? Here we show some head to head comparisons that can help you decide.
An in-depth discussion of this topic was also captured by MSU’s “Bug Bites” last year, and I’ve included the video below.
This post on poinsettia problems was contributed to by Drs. Chevonne Dayboll and Sarah Jandricic.
When poinsettias get problems, they always seem to hit hard and fast. Things like whitefly, Lewis mite, root rots, and nutritional issues can all quickly derail a quality crop. This is why scouting might be more important in this crop than any other.
Here’s a month by month guide on what you should be looking for to prevent small problems from becoming big issues.
Lately, you might have heard a lot about a certain invasive pest in the news – the Spotted Lanternfly. This objectively beautiful but damaging species is a pest of certain trees, grape vines, and other horticultural crops.
Spotted in North America as early as 2012, specimens of the invasive spotted lanternfly have now been detected in Michigan, New York and Quebec. Do Ontario ornamental crop growers need to be worried? Keep reading to find out!*
(*This post was was originally posted on the ONFruit blog and was amended by S. Jandricic for relevance to the ornamental industry).
What is a Spotted Lanternfly?
Spotted Lanternfly (Lycorma delicatula) is an invasive plant hopper, originally from Asia. They feed on the sap of plants. As with any sap-sucking pest (like aphids and whitefly), their feeding can causing wilting and dieback of plants when present in high numbers. Like aphids and whitefly, they also produce copious amounts of honeydew, resulting in the growth of sooty molds.
Crops at Risk
There are over 70 documented hosts in North America. The main hosts include grapevines, fruit trees (apple, peach, plum, cherry), hops and hardwoods (black walnut, maple).
However, certain ornamental tree and vine species can also be hosts, including Japanese maple, lilac, and virginia creeper. The biggest red flag for the ornamental industry on this list of susceptible host plants is certainly roses, including Beach and Japanese rose shrubs. Thankfully, other common ornamentals grown by the greenhouse floriculture industry (including perennials and outdoor cut flowers), do not appear to be hosts.
Reports of economic injury in Pennsylvania, where this pest has established, have occurred in commercial vineyards, where swarm feeding has resulted in yield loss, decreased sugar content in harvested grapes, and weakening and death of vines. For trees, heavy feeding from spotted lanternfly feeding doesn’t usually kill the tree but is a stressor and some dieback can occur.
Early Detection is Critical
With ornamental trees and shrubs, as well as roses, on it’s list of potential targets, it essential that ALL agricultural operations keep their eye out for this pest, ESPECIALLY when receiving shipments from areas where Spotted Lanternfly has been spotted or is established (see Distribution, below).
Although established populations have NOT been found in Canada (yet), it’s moving closer and closer to our Ontario border with recent detections in New York and Michigan.
Early detection of any spotted lanternfly sightings is CRUCIAL so we can act quickly and limit its spread. Report any suspected finds immediately to the Canadian Food Inspection Agency (CFIA) online or by calling 1-800-442-2342.
Native to Asia, spotted lanternfly was identified in Pennsylvania in 2014. Despite containment efforts, this pest has spread further and established populations are now found in various regions across the United States.
In September 2020, the CFIA confirmed the identification of two dead spotted lanternflies on commercial trucks travelling from Pennsylvania to Quebec, illustrating the pests’ capacity for being spread quickly over large geographic areas by human activities.
The spotted lanternfly is an excellent hitchhiker. Adults can cling to cars and trucks moving at high speeds for long distances. Females indiscriminately lay eggs on any smooth surface (vehicles, stones, lawn furniture, etc.); egg masses are difficult to detect, can be moved over great distances, and represent the life stage adapted to overwintering.
With so many different pathways and potential points of entry, monitoring presents a big challenge. In 2016 and 2018, OMAFRA monitored high risk areas using sticky tree bands. No spotted lanternfly was detected, but it was like looking for a needle in a haystack. Ontario is a big province!
In 2019, a Canadian Spotted Lanternfly Education and Outreach Committee was formed. Members include the Invasive Species Centre, CFIA, OMAFRA, Ontario Federation of Anglers and Hunters, industry representatives and city foresters.
Currently, the best plan of attack for Ontario is to have as many trained eyes as possible on the look-out for this unique-looking invasive insect.
Know What to Look For
In the mid-Atlantic states, overwintering egg masses are laid through the fall. The egg masses usually have about 30 to 50 eggs and are laid in parallel lines.
Nymphs begin to appear in the late spring. They feed and move almost constantly. Keep a close eye on grapes, tree-of-heaven, black walnut, butternut, willow, birch, sumac and roses around your property as nymphs seem to prefer these hosts. Late instar nymphs tend to cluster together on preferred hosts, such as tree-of-heaven and black walnut.
Adults appear mid-July and are active until they are killed by cold temperatures. In vineyards, adults tend to show up along borders first. There are reports that spotted lanternfly adults are poor flyers; however, they can travel a long distance with the right conditions.
There is one generation of spotted lanternfly per year. Recent observations show that spotted lanternfly does not require tree-of-heaven to survive, but comprehensive information on host use requires additional research.
Management in the United States
In the US, research is being conducted to develop better tools for monitoring and management. You will find the latest information on Penn State Extension’s spotted lanternfly website.
Current management in the US includes:
Remove and destroy egg masses –Scrape off into a container and place in alcohol (hand sanitizer, rubbing alcohol, other). Check vehicles, farm equipment and other hard surfaced items thoroughly for egg masses if coming from infested areas.
Remove tree-of heaven – May help reduce numbers but may not be practical if present in large numbers. Herbicides can be applied to control suckers. Since other hosts may prove suitable to complete development, attempts at eradicating tree-of-heaven as a management strategy may prove ineffective.
Use sticky tree bands – Helps reduce numbers of nymphs. To avoid catching non-target organisms, use large-gauge mesh over the band, or alternatively, inward-facing sticky bands to intercept nymphs as they climb up host trees. Research to develop better traps is ongoing.
Encourage natural enemies – This includes spiders, assassin bugs, praying mantis and others that prey on spotted lanternfly. Relying on natural enemies alone may not be enough to control a high population. Parasitic wasps have been identified in China but require evaluation for non-target effects.
Use insect-pathogenic fungi – Fungal pathogens, such as Beauveria bassiana, are being evaluated. The entomopathogenic fungus Baktoa major has been found in association with SLF in Pennsylvania and appears to be highly virulent against the pest.
Apply insecticides – Products containing bifenthrin, thiamethoxam, dinotefuran, carbaryl, fenpropathrin, malathion or zeta-cypermethrin provide effective control of nymphs and adults. Chlorpyrifos is the only active ingredient that gave high mortality of eggs. Mineral oil has shown egg mortality of up to 71%. For landscape trees, they have used tree injections, trunk sprays or soil drenches with certain neonicotinoid insecticides with excellent results.
Where We Go From Here
Although Spotted Lanterfly hasn’t shown up in Ontario yet, OMAFRA is already taking steps besides monitoring. As we do not have any registered uses for the control of spotted lanternfly in Canada, this pest has been prioritized through the Minor Use Program for high-risk crops.
Although this pest may seem concerning to many – remember – we’ve been through this before (I’m looking at YOU, Japanese beetle!). As with JB, different agencies within Canada will work together with growers and industry groups to develop action plans to both protect Canadian crops and maintain market access, should this pest make it to Ontario.
With the holiday season almost upon us, it’s time to turn our attention to Spring bedding crops. Although here for a brief window, the diversity of these crops means you’re bound to encounter some sort of disease and insect problems.
One way you can head off issues is to plan and prepare now. This post from January 2020 has important tips on sanitation for common spring crop diseases, dipsandearly sprays to prevent key pests, as well as tips on where to spend your biocontrol dollars.