What To Look For This Summer

Summer is usually the time of more intense insect and mite pest pressure, simply because temperatures are warmer and many major pests develop faster – or in some cases, just develop, which they do not do outdoors in a northern winter.

Mites and insects are “cold-blooded” animals that are affected by temperatures.

Feeding, reproduction, development time and survival are mostly dependent on temperature, but moisture, humidity, plant health, nitrogen level, and soil/potting mix contribute as well. Following are a few examples of greenhouse and nursery insect and mite pests that do best when temperatures warm.

Two-spotted spider mites

Two-spotted spider mites are warm-season mites, doing best when temperature are higher. It takes about 28 days to develop from egg to adult at a cool temperature range of 50°–68°F, but only about 8 days at a warmer temperature range of 77°–95°F. You can easily see that more spider mite generations in a given amount of time will occur at high rather than low temperatures.

Fortunately (or not, depending on your point of view), plant injury caused by two-spotted spider mites appears quickly on most plants and can be detected using a good scouting and monitoring program. Applications of effective miticides can then be made to stop the infestation’s spread.

Western flower thrips

Western flower thrips, or WFT, generally cause more problems on greenhouse-grown plants, but can also affect plants grown outdoors. WFT are warm – but not too hot – weather pests. The ideal temperature for development and reproduction is about 80°F. WFT development takes place between about 50 to 90°F. Thrips can survive temperatures lower than 50°F, but there is no development. Above about 95°F development again stops. With a warm temperature range of 65–95°F the egg to adult cycle is about 10 to 14 days.

At cooler temperature ranges, the egg-to-adult cycle extends to as long as 30 to 40 days. Growers have reported thrips infestations that seemed to appear overnight. Unless you believe in spontaneous generation, this seems unlikely. The probable causes for these “overnight” infestations are:
1. Movement into the crop from adjacent areas;
2. Favorable environmental conditions allowing the thrips – which were already there at low numbers – to increase rapidly.

Have I mentioned having a good scouting and monitoring program?

Leafminers

Leafminers develop from egg to adult in 14 days at 95°F to 64 days at 59°F. Other species have different lower and upper limits for development, but development trends are similar – warmer temperatures result in faster development. Leafminers generally do best when plants are high in nitrogen.

Primary Liriomyza leafminer injury is from the larvae feeding within leaves, making a narrow winding trail, or mine. Both greenhouse and outdoor crops can be infested. Adult leafminer flies puncture leaves for feeding and egg-laying, and the small white spots will indicate leafminer activity. Leafminers have a very wide host plant range.

Whiteflies

Bemisia whiteflies are warm weather pests, with temperatures making a big difference in development times – 16 days at 86°F to 31 days at 68°F. A whitefly infestation will reduce a plant’s value, and high numbers can reduce plant growth or vegetable yields. Bemisia whiteflies can cause leaf spotting, white stem and bract deformation on poinsettia. Honeydew from whiteflies makes leaves and fruits sticky and is a substrate for black sooty fungus. Whiteflies can transmit many plant viruses affecting vegetable and ornamental plants.

Aphids

Common aphids on ornamental crops are the green peach aphid (Myzus persicae) and melon/cotton aphid (Aphis gossypii), but numerous other species can be found on herbaceous and woody plants. Both melon aphids and green peach aphids will infest large numbers of host plants. Although many aphids generally do better at warmer temperatures, the best temperatures for development vary with the species. For example the chrysanthemum aphid develops best at 68°F, the green peach aphid at 73°F, and the melon aphid at temperatures above 75°F. When temperatures are above 86°F and the relative humidity is above 85 percent, green peach aphid longevity and reproduction is reduced – conditions that are likely to slow (or stop) reproduction of just about anything!

Managing summer pests

Weekly scouting of crops and the use of sticky traps for pests attracted to them are the most practical methods for detecting insects and mites and keeping tabs on how the management program is going. The bottom line here is that insect and mite generations are generally shorter at warm temperatures than at cool temperatures, and your management program needs to be adjusted accordingly.

Foliar sprays will need to be applied more often when it’s warm. However, on crops where it is known that a certain insect or mite will probably appear, it is acceptable to apply pesticides preventively – especially systemic products as drenches or granules, which need time to move up into the plants.

On outdoor crops, scouting and monitoring should be done as well, and there are methods to assist the process involving so-called plant phenology charts. Just as development of insects and mites depends on temperature, so does plant development. Clever and observant folks have long associated appearance of pests with development stages of certain plants. Other clever folks have put this information into charts that help with decision-making. Phenology charts are only accurate over a limited area – maybe a state or part of a state – so growers need to use information for their area. Again, this information will help if foliar spray applications are going to be used for control.

If the goal is to use a preventative management program with soil-applied, systemic products, applications need to be made before the appearance of the pest – sometimes well before – to minimize plant injury.

Leave a Reply

Latest Stories
hoffman-new-greenhouse-feature

September 30, 2016

How Hoffman Nursery Invests In Technology In Response T…

The North Carolina-based ornamental and native grasses producer recently invested in greenhouse structures and advanced automation to help increase efficiency.

Read More
cannabis-planted-in-a-greenhouse

September 29, 2016

The 10 Most Common Misconceptions About Greenhouse Cann…

In an emerging market such as cannabis, there can be a lot of bad information out there. One greenhouse supplier points out some common myths.

Read More

September 28, 2016

Pennsylvania Greenhouse Grower Applying For Cannabis Li…

Allen Wagner of Wagner’s Greenhouse in Grandview, PA, hopes to become one of 25 applicants — among as many as 150 — chosen for a grower-processor license.

Read More
finneran bee on snakeroot

September 28, 2016

Which Annuals And Perennials Are Good For Pollinators?

If you are a grower looking for information on producing plants that are safe for pollinators, or which plant types can be marketed as good food sources for bees, the new publication “Protecting and Enhancing Pollinators in Urban Landscapes” provides a good resource.

Read More
The-Capitol

September 28, 2016

How The November Election Might Affect The Legalization…

National polls indicate Americans are largely divided on the topic, while this year’s presidential candidates generally feel it’s a state issue.

Read More
tomato spotted wilt virus angular-necrosis-of-leaves-and-plant-stunting

September 28, 2016

Tips For Managing Tomato Spotted Wilt Virus In Mums

According to a report from Michigan State University, symptoms of tomato spotted wilt virus on chrysanthemum include yellow blotching and rings, necrotic lesions, and stem collapse.

Read More
cannabis-crop-protection

September 27, 2016

Washington State Outlines Pesticide Criteria For Cannab…

The state has also compiled a searchable list of pesticides that fit the criteria for use on marijuana.

Read More
Vogel Alcove NGB Therapeutic Grant Winner

September 27, 2016

National Garden Bureau Announces Horticulture Therapy G…

The NGB’s annual grant program, Growing for Futures, recently selected three therapeutic gardens that will receive grants totaling $5,000.

Read More
phlox-fashionably-early-flamingo-walters-gardens

September 27, 2016

Walters Gardens Partnering With Darwin Colombia On Unro…

Beginning in spring 2017, Darwin Colombia will offer unrooted cuttings of more than 40 varieties of Walters Gardens’ new genetics, including many popular genera such as Agastache, Monarda, Nepeta, and Phlox.

Read More
totalgrow-night-and-day-management-boom-lighting-venntis-feature

September 27, 2016

Check Out The Latest In Lighting Technology For Greenho…

Manufacturers are developing several innovative lighting systems that can help growers save on energy efficiency, while improving plant quality. Here’s a look at some of their newest offerings.

Read More
cuttings-facility

September 27, 2016

How Global Suppliers Of Unrooted Cuttings Are Working T…

The world’s top vegetative producers discuss how they continue to evolve to overcome challenges and embrace opportunities to help growers and the varieties supply chain.

Read More
Streptocarpus Ladyslippers Grape Ice (Green Fuse Botanicals)

September 27, 2016

9 New Blooming Potted Plants To Jazz Up The Home And Ga…

Blooming potted plants are the ideal gift for anyone, from a homesick college student to a spouse in need of some cheering up. Check out nine these new introductions hitting the retail market in 2017.

Read More

September 27, 2016

Kitchen Counter Gardening Leads Garden Media Group̵…

This year's list includes several items around healthy living and eating, from gardening indoors year-round, to "forest bathing."

Read More
bruce-butterfield-and-ngs-image

September 27, 2016

Bruce Butterfield, National Garden Survey Researcher, D…

The man who headed up the National Gardening Survey for the past 35 years, Bruce Butterfield, has died. He was 67 years old. Butterfield’s work with the National Gardening Survey gave the green industry a reliable tool to understand consumer gardening practices and spending. Bruce Butterfield started his career as the Market Research Director at the National Gardening Association in 1978 and continued that same work until his death on September 5 as the Research Director at GardenResearch.com. “These many years of experience doing market research about gardeners and gardening trends gives him a unique understanding of who gardeners are, what they need and want, why they buy the products they do, where they shop, how gardening trends have changed in the past, and where they are headed in the future,” his bio on GardenResearch.com reads.       Butterfield was also behind What Gardeners’ Think and the Environmental Lawn […]

Read More

September 26, 2016

How Even An Overworked Plant Retailer Can Predict Consu…

Years ago, I read an article about Pottery Barn and the women who were making it a success. It was eye-opening to realize that a glossy, national chain like Pottery Barn used to buy products in a similar way garden retailers do. There was one section of that article that really caught my imagination. It was the profile of Celia Tejada, the woman who moved Pottery Barn from buying products from outside vendors to designing their own products. When Tejada joined Pottery Barn, she instructed her entire staff to begin keeping an eye out for things they liked, no matter how minor. So if they were at a restaurant with friends, or walking along a street and something caught their eye, they were to either buy it or photograph it and place it in a room set aside for these kinds of inspiration. When it came time to select themes for the […]

Read More
urban-outfitters-logo-feature

September 26, 2016

Terrain’s Parent Company Breaks Impass For Waterl…

There’s been a development in the stalled plans for a new Terrain garden store from Urban Outfitters on the former Waterloo Gardens location. In a letter to Easton Township, PA, officials, Urban Outfitters’ Chief Development Officer J. David Ziel says the company is removing a key element that had met strong resistance from the community around Devon Yards, its term for the development plan on the former Waterloo Gardens site. Devon Yards will no longer include a four-story apartment building in its “lifestyle center” project, Ziel wrote. But it will still include its third Terrain store, a large format Anthropologie, and several eateries. The planned apartment building had created friction with local residents, Mainline Media News reported back in April. While residents welcomed the retail aspects of the plan, they felt a large apartment building would change the character of the community. The developer who will work on the project, […]

Read More
Orius_June 2015

September 25, 2016

Peace Tree Farm Hosting Biocontrols Event In October

“Advanced Greenhouse Biocontrols for Ornamental and Vegetable Producers” will feature advice from biocontrol authorities Lloyd Traven and Suzanne Wainwright-Evans.

Read More
sbi-software-triumph

September 25, 2016

Greenhouse Software Suppliers Offering A Range Of New S…

Want to know what some of the leading software suppliers are doing to address the ever-evolving needs of their greenhouse customers? Here’s a brief update.

Read More
[gravityform id="35" title="false" description="false"]