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
Cannabis Structure

August 23, 2016

5 Factors To Consider In Your Cannabis Structure

Along with the size and specs of your greenhouse, it's also important to focus on ventilation, light deprivation, benching, irrigation, and odor control.

Read More
Penn State Plant Bud

August 23, 2016

AmericanHort Is Helping Plant Importers Adjust To New R…

A report from Craig Regelbrugge at AmericanHort says the government is implementing a streamlined system for imports, in which all required data will be submitted electronically through a single window.

Read More

August 23, 2016

Kick Spring Sales Up A Notch With 18 New Plant Introduc…

It’s time to look forward to the spring season and what plants will get your business off to the right start. These 18 new cultivars have all the traits of good breeding — uniform habits, bold colors, showy blooms, good vigor, and excellent branching.

Read More
Bees And Pesticides

August 23, 2016

Studies Offer Conflicting Views On Neonic Effect On Bee…

How much exposure to neonicotinoids do bees need before their health becomes affected? That’s the question two research teams look to answer.

Read More

August 23, 2016

Gardens Alive! Parent Company Buys Zelenka Farms

  Zelenka Farms, which has been in Chapter 11 bankruptcy, says LM Farms, which owns Gardens Alive!, has purchased the company and all of its assets. BFN Operations LLC and its affiliated entities, d/b/a Zelenka Farms, operated one of the largest wholesale nurseries in the U.S. Its products include shrubs, trees, perennials, roses, and groundcovers. The owners of Gardens Alive! have successfully purchased several other companies from bankruptcy and are experienced nursery managers. Niles Kinerk, Chairman of LM Farms, stated that “the opportunity to purchase Zelenka Farms assets and to continue the turnaround that is well underway is exactly the kind of opportunity that we look for. We understand the efforts of the management team led by Eric Ek and others have been successful, and we will support the management team in the coming months and years.” Zelenka Farms operates its six facilities across the key growing regions in the […]

Read More
Chrysanthemum Aphid

August 22, 2016

How To ID And Manage Black Aphids In Chrysanthemums

Growers in Michigan have recently been reporting a higher presence of this pest. Here are some tips on how to control it.

Read More
LuxFlora - feature

August 22, 2016

Check Out Luxflora’s International Adventures In Europe

A new, women-led professional organization provides its members the opportunity to gain insight, develop ideas, and build connections on its annual international trip.

Read More
Cannabis Crop Protection

August 22, 2016

Cannabis Group Stays Focused On Consistent Standards Fo…

The Foundation of Cannabis Unified Standards (FOCUS), is an independent, third-party, not-for-profit organization, is in the process of developing cannabis-specific standards for everything from cultivation and extraction to packaging and retail.

Read More

August 22, 2016

Syngenta

Growers have new broad-spectrum fungicide options with new Segovis and Mural, as well as a new systemic insecticide with Mainspring GNL.

Read More

August 22, 2016

PL Light Systems

With the introduction of PL Light System’s new HortiLED light systems, growers no longer have to choose between quality and energy savings. Three different systems, designed for both standard and multilayer application, deliver exceptional uniformity and efficiency.

Read More

August 22, 2016

Emerald Coast Growers

Emerald Coast Growers has answers to the top trends in gardening with Chick Charms Sempervivums, two beautiful and sterile Miscanthus varieties, and the pollinator-friendly Bee You Monarda series.

Read More

August 22, 2016

PanAmerican Seed

The gorgeous large flowers of Megawatt begonias offer high-voltage color in the landscape, pots or baskets. Easily grown from seed, Megawatts come in four colors and are accompanied by eye-catching free retail kits including posters and bench cards.

Read More

August 22, 2016

PanAmerican Seed

PanAmerican Seed introduces exciting new multi-species combos from seed to its Plug & Play combo program. Trialed and proven by growers, varieties are carefully selected to grow and bloom together and make consumers come back wanting more.

Read More

August 22, 2016

How Bad Plant Pricing Can Hurt A Good Retailer

Greenhouse Grower RETAILING's pricing survey finds that the most profitable pricing method is used by only 8% of plant retailers.

Read More

August 22, 2016

IGC Chicago Scores Big With Attendees And Exhibitors

The 10th anniversary of the annual event at Chicago’s Navy Pier drew a record number of first-time attendees, while exhibitors reported higher sales than ever.

Read More
Leaf Septoria In Cannabis

August 21, 2016

Three Diseases To Watch For In Cannabis Production

The development of root rot, powdery mildew, and leaf septoria can damage cannabis to the point of complete crop loss.

Read More
Growers Supply Workshop

August 21, 2016

Learn Tips On Greenhouse Management During Growers Supp…

The hands-on workshops take place Sept. 13-15 in Iowa and Oct. 12-14 in Connecticut and feature new trends and innovations in controlled-environment agriculture.

Read More
Coreopsis-UpTickCream-19793-DarwinPerennials

August 20, 2016

Growing Tips On Coreopsis UpTick Series From John Wilso…

Editor’s Note: In this new feature, the Greenhouse Grower varieties team will choose one noteworthy variety each month we think is worth bringing to your attention. Then we’ll share growers’ and breeders’ perspectives on the best ways to produce it successfully at your operation. This month we focus on the hardy Coreopsis UpTick series, winner of Greenhouse Grower’s 2016 Industry’s Choice Medal of Excellence for Breeding. Growing Tips From John Wilson, Seville Farms When asked about producing Coreopsis UpTick, John Wilson says he doesn’t have much to say because it was so easy to grow. Wilson, a Corporate Grower for Seville Farms, says based on the new series’ strong performance during the trialing he has done so far, the nursery ordered a large quantity of the plants for future growing. “If breeders were looking to come up with something that says ‘wow,’ they have done it with the UpTick Series,” […]

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