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OVERVIEW:

Broad mites (Polyphagotarsonemus latus) are tiny tarsonemid mites which are difficult to scout for, and may spread on clothing, air currents, or even other pests. They are pests of 60 plant families, which include food and ornamental crops (Zhang 2003). Affected plants include pepper, tomato, cucumber (Heinz et al. 2004; Zhang 2003), soybeans, citrus (Vacante and Kreiter 2017), blackberry, raspberry, strawberry (Gobin et al. 2017), African violet, begonia, chrysanthemum, cyclamen, dahlia, gloxinia, fuchsia, gerbera, hibiscus, impatiens, and ivy (Heinz et al. 2004; Zhang 2003).

DESCRIPTION:

Broad mites are very small (0.007” long; Heinz et al. 2004; Vacante and Kreiter 2017) and have varying colors that are influenced by the host plant (Zhang 2003; Vacante and Kreiter 2017). Their bodies are typically hard and shiny (Gerson and Weintraub 2007) and the females will have a faint white stripe in the center of their backs (Zhang 2003; Vacante and Kreiter 2017). Males are shorter than females and tapered toward the rear (Zhang 2003). Positive identification requires slide-mounted specimens and a skilled acarologist but knowing the host plant and being able to recognize the signs and symptoms can provide an indication of their presence. A useful diagnostic for broad mites is their eggs, which look like small footballs with rows of protruding white spots.

DAMAGE:

Broad mites feed on buds, blossoms, new leaves, and young fruit (Gerson and Weintraub 2007; Vacante and Kreiter 2017; Weintraub et al. 2017; Zhang 2003) which results in damage similar to that from hormonal weed killers (Zhang 2003). Generally, this manifests as bronzed leaves with down-curling margins, aborted and distorted buds and vegetation, twisted shoots, and misshapen or russeted fruit (Vacante and Kreiter 2017). The feeding prevents flower and fruit development on pepper seedlings and causes flower loss and silvering of fruit on older plants (Vacante and Kreiter 2017). Damage to eggplants is similar to that of peppers (Vacante and Kreiter 2017). To gerbera, leaves can split or crack open resulting in a rugged look, and flowers have distorted and discolored rays (Vacante and Kreiter 2017). The signs and symptoms can persist for multiple weeks following the removal of mites (Vacante and Kreiter 2017).

LIFE CYCLE:

The optimal conditions for broad mite development are moderate temperatures (77F), high humidity (90-100%), and low light intensity (Heinz et al. 2004; Vacante and Kreiter 2017). Broad mites are normally active throughout the year in greenhouse situations, with reproduction slowing in cooler months (Vacante and Kreiter 2017). Males deliver dormant females to new growth (Gerson and Weintraub 2007; Vacante and Kreiter 2017). Females oviposit approximately 25-50 eggs during their 10-11 day lifespan within the hollows of the lower leaf surface, and on young fruit (Zhang 2003; Vacante and Kreiter 2017). Fertilized eggs produce females, while unfertilized eggs produce males (Vacante and Kreiter 2017). The emerging stage is called a larva and lasts for one day (Vacante and Kreiter 2017). It takes approximately four more days until they develop into adults (Vacante and Kreiter 2017). They can disperse to other plants and plant parts by walking, wind, human transport, and by latching onto the legs of whiteflies (Gerson and Weintraub 2007; Weintraub et al. 2017; Zhang 2003).

MONITORING TIPS:

Keep a close eye on plant species that are likely to be attacked by broad mites. Greenhouse plants that are “magnets” for broad mites include: Zonal geraniums, New Guinea impatiens, thunbergia, torenia, verbena, rieger begonias, scaevola, angel wing begonia, ivy geranium, and buddleia (Lindberg 2017a). Examine the undersurfaces of young leaves, crevices between leaves and stems near apical growth and flower buds (Zhang 2003) for their presence. Use a 20x hand lens or microscope (UCONN IPM 2020). Damage is generally not noticeable until 20-30 days after the initial infestation and the mites have likely moved onto neighboring plants at this point, so scouting efforts should focus on surrounding vegetation (Lindberg 2017b).

BIOLOGICAL CONTROLS:

Which predatory mite to apply will depend on the host plant, environmental conditions, and other biocontrols being used. Predators of tarsonemid mites include Neoseiulus cucumeris, Neoseiulus californicus, and Amblyseius swirskii (Heinz et al. 2004; Weintraub et al. 2017). Preventative releases of predatory mites should be used when you have plants that are susceptible or have a history of broad mites (Jandricic 2015).

Neoseiulus cucumeris will feed on pollen, thrips, and other small mites in addition to broad mites (Weintraub et al. 2017). They do not establish well on tomatoes but will establish on sweet peppers when pollen and prey are present, and on cucumber when prey is present (Weintraub et al. 2017). On greenhouse peppers, good broad mite control was achieved by releasing 600 N. cucumeris on each or every other plant (Gerson and Weintraub 2007). Neoseiulus cucumeris performs as well as A. swirskii during winter months in temperate greenhouses and may be the desired choice in winter because of its lower price (Buitenhuis et al. 2015).

Amblyseius swirskii is an aggressive generalist predator of broad mites, tomato russet mites, whiteflies, and thrips (Buitenhuis et al. 2015; Weintraub et al. 2017). Additionally, they feed on pollen and applications of supplemental food can enhance their success (Gobin et al. 2017). In a greenhouse trial on Rhododendron simsii, A. swirskii achieved better control of broad mites than repeated applications of abamectin (Gobin et al. 2017). In greenhouse sweet pepper, good control was obtained by releasing the mites at rates of 5-10 per square foot (Gerson and Weintraub 2007). Releases of 63 mites per plant effectively controlled broad mites in field-grown peppers and eggplants (Stansley and Castillo 2013). Avoid the use of A. swirskii if you are also using Aphidoletes aphidimyza for aphids. They are known to devour the eggs of A. aphidimyza and can disrupt aphid control (Messelink et al. 2011).

Neoseiulus californicus are generalist predators with a preference for Tetranychus spp. mites (Zhang 2004). They are able to tolerate lower humidity and higher temperature than the last two mite species. Greenhouse releases of one predator for every 5-15 prey considerably reduced broad mite densities on limes for weeks after the initial release. Similar results were obtained on field-grown limes during the moderate winter-spring conditions of Florida. Neoseiulus californicus could not keep up with a broad mite population boom during the hot and humid summer-fall (Phytoseiidae 2011). Neoseiulus californicus can be an excellent choice if you also have a history of spider mites.

USING CHEMICALS:

Broad mites are excellent at hiding in curly leaves and unexposed areas, making whole-plant coverage with pesticide sprays difficult (Zhang 2004), which is why preventative releases of predatory mites are so important. However, there are some conditions in which mite predators are not able to keep up with the population growth of broad mites, and biorational pesticides should be used. Dips of mineral oil can be used to clean up incoming plants or cuttings, and entomopathogenic fungi may be sprayed in propagation domes where the humidity is high and conducive to their germination. For extreme infestations, knockdowns with sulfur products may be warranted. If that is the case, do not combine sulfur with oils. Sulfur and oil products are highly incompatible and will burn your plants when used together.

OTHER MEASURES:

If there is a small number of infested plants, they must be bagged and eliminated before any further spread (Heinz et al. 2004). Because of the wide host range of broad mites, controlling weeds inside and outside of greenhouse structures might also reduce the overall pest abundance and carryover from previous crops (Vacante and Kreiter 2017). Always inspect incoming plant material to ensure that it is free of pests. Dipping the foliage of cuttings in a pesticide can help lessen the incoming pest load (Vacante and Kreiter 2017). Host plant resistance has not been thoroughly investigated for broad mites, but in general healthier plants are able to cope better with feeding damage. Soil drenches of beneficial microbes have induced foliar resistance against different pests and should be investigated for broad mites.

Author: Alec Blume, 2020.

References

Buitenhuis R, Murphy G, Shipp L, Scott-Dupree C. Amblyseius swirskii in greenhouse production systems: a floricultural perspective. Exp Appl Acarol. 2015;65(4):451-464. doi:10.1007/s10493-014-9869-9

Gerson U, Weintraub PG. Mites for the control of pests in protected cultivation. Pest Manag Sci. 2007;63(7):658-676. doi:10.1002/ps.1380

Gobin B, Pauwels E, Mechant E, Audenaert J. Integrated control of broad mites in ornamental plants under variable greenhouse conditions. IOBC-WPRS Bulletin 2017;124:125-130.

Heinz KM, Driesche RV, Parrella MP. Biocontrol in Protected Culture. Ball Pub.; 2004.

IPM Scouting and Decision Making. UCONN IPM website. http://ipm.uconn.edu/pa_greenhouse/. Accessed April 12, 2020.

Jandricic S. Banishing Broad Mite. OnFloriculture blog website. https://onfloriculture.com/2015/06/02/banishing-broad-mite-new-post-in-floriculture-ipm-blog/. June 2, 2015. Accessed April 12, 2020.

Lindberg, H. Attention scouts: Crops that are insect “magnets” in the greenhouse. MSU Extension website https://www.canr.msu.edu/news/crops_that_are_insect_magnets_in_the_greenhouse. February 2, 2017. Accessed April 12, 2020.

Messelink GJ, Bloemhard CMJ, Cortes JA, Sabelis MW, Janssen A. Hyperpredation by generalist predatory mites disrupts biological control of aphids by the aphidophagous gall midge Aphidoletes aphidimyza. Biological Control. 2011;57:246-252.

Phytoseiidae. In: Mites (Acari) for Pest Control. John Wiley & Sons, Ltd; 2007:173-218. doi:10.1002/9780470750995.ch26

Stansly PA, Castillo JA. Control of Broad Mites, Spider Mites, and Whiteflies using Predaceous Mites in Open-field Pepper and Eggplant. Proceedings of the annual meeting of the Florida State Horticultural Society.  2013;122:253-257.

Vacante V, Kreiter S. Handbook of Pest Management in Organic Farming. CABI; 2017.

Weintraub PG, Recht E, Mondaca LL, Harari AR, Diaz BM, Bennison J. Arthropod Pest Management in Organic Vegetable Greenhouses. Godfrey L, Siebert MW, eds. Journal of Integrated Pest Management. 2017;8(1). doi:10.1093/jipm/pmx021

Zhang ZQ. Mites of Greenhouses: Identification, Biology and Control. CABI; 2003.

Keep an eye out for the Emerald Ash Borer, Agrilus planipennis. It has been detected in 24 states, including our state of Washington, and parts of Eastern Canada. Civic involvement in pest ID and entomology is a powerful thing. Please inspect your local trees. 

In Washington, our native "Oregon Ash" Fraxinus latifolia is of particular concern. Additionally white ash (F. americana) and green ash (F. pennsylvanica) are common targets as they are often planted as ornamental shade trees. If you suspect EAB, please call 1-800-443-6684.

See this link for more information regarding ID, and what you can do. 

It's commonly known that there are pathogenic nematodes which can cause damage to plants, but did you know that there are species of nematodes which are actually used to control pests? We refer to these beneficial nematodes as entomopathogenic nematodes. We like to think of beneficial nematodes as a fantastic starting place for those new to biocontrol. Why? Because they truly work so well, AND they are compatible with many pesticides and fungicides. In other words, even conventional growers can seamlessly integrate nematodes into their operation without forfeiting the use of various conventional pesticides they may be using in their IPM program. Sound too good to be true? We know these little roundworms are extremely tough and efficacious. As an example, nematodes can actually freeze their metabolism in the absence of adequate food or oxygen, but continue to survive until circumstances improve. This state is called "cryptobiosis". Additionally, after the 1981 Columbia space shuttle disaster, nematodes were the only known survivors.

When you are considering which nematodes to purchase, consider not only the correct speci you need to control the problematic pest at hand, but also the production method. Nematodes produced "in vivo" tend to yield a very high numbers of infective juveniles which are largely responsible for the killing of pests. This production method utilizes wax worm cadavers to breed healthy nematodes, which contain a very high level of infective bacteria (see the featured diagram of the life cycle). In vivo nematodes also requires a much lower application rate per sq. ft. of soil when compared with "in vitro" nematodes. 

Our Sierra nematodes are produced in vivo and yield exceptional results for our customers. For more information about Sierra nematode production, species available, and some guidelines for speci and pest pairing, refer to this link or feel free to contact us directly for more information.

When it comes to your IPM program, are you employing all the stops? Are you adequately considering these components of your IPM program?

1)Removing debris (cultural control)- fungal pathogens (i.e. botrytis).

2)Properly sanitizing surfaces, pots, soil, and tools.

3)Stopping entry and vectoring at the door!

Proper sanitation is imperative for maintaining a good integrated pest and disease management program and stopping pests “at the door” should be the first line of defense. Within the larger industry, there are an array of needs in the sanitation department. Without being able to touch on them all, let’s talk about your feet! As we approach fall weather, pests are certainly looking to hitch a ride into indoor environments and greenhouses. That said, vectoring pests in and out of various facilities, greenhouses, or rooms, is a potential problem all season long. How are your growers and employees moving through the facility? Avoid allowing growers to work in contaminated areas and then move to propagation later in the day. Consider supplying a change of clothes and even crocs or boots for employees. 

We work to stay abreast of all the updates and changes in the industry and in biocontrol and share that information with all of you. That said, some trusted principles and products have not changed for decades and remain trusted industry standards.

To assist with this continued concern, we made have ordered in products to make it easy for our customers. Whether you are moving from stock to finishing areas, or from outdoors to indoors, having a sanitation mat is critical for vectoring reduction. For fall, we are combining the long-standing industry sanitation product, Green Shield, with the sanitation mats as a package deal. We don’t want you to call us in crisis!

For $147 you can receive 1 gallon of Green Shield with our favorite type of sanitation mat.

We’ve seen so many changes over the last couple years, within our business as well as the many varied sectors of organic agriculture, conventional agriculture, and larger horticultural industries. The use of biocontrol is expanding with each year, and with that, our business has been growing. In fact, we just moved to a larger facility to accommodate additional warehousing of biological products and to expand the capacity of our shipping facility. Last year, we started our ecommerce online store to accommodate customers who prefer to shop online. As an extension of that, we are working to keep our blog updated with pertinent information for all of you working to continually improve and learn. We pride ourselves in our customer service and go out of our way to host workshops, make ourselves available to customers, and to openly share pertinent information to all of you who are trying shore up your pest management.

It’s estimated that 40% of the world’s food production is lost each year due to pest and diseases related failure. Our goal is to provide tactics and products in order to properly manage pests, while remaining environmentally conscious. Additionally, we encourage growers to develop natural habitats for hosting beneficial populations. We recognize that the growth we are experiencing is an industry-wide and environmental success. Pest resistance to conventional chemicals is not going away, while the domestic and international tightening of chemical regulation is on the rise. As growers experience the limitations of chemicals, they are now leaning on biological controls and biologically based practices. Meanwhile, consumers are asking that their products be produced using clean practices, whether it be ornamental crops, food crops, herbs, cannabis, or the plant based inputs of their supplements…EVERYTHING! We find this grassroots movement extremely exciting and encouraging!

So welcome to the green side! We are here to assist.

The annual Pacific Northwest Vegetable Association Conference will be held at the Three Rivers Convention Center in Kennewick, WA on November 14th & 15th. Come join other growers, vendors, and support sponsors for talks about the industry, breakout speakers, and social events. Alison will be speaking about IPM in organic agriculture at 11:30am on November 15th (summary below). See you there!

Biocontrol Bandwidth:  Biopesticides , Beneficial Insects or Both?
Vegetable growers are increasingly relying on biological controls for both pest and disease control. This session will examine some of the evolving applications and approaches, and help you add more options to your evolving toolbox. Application protocols for beneficial insects vary greatly, so this presentation will give and overview various release methods for small to large growers. We’ll cover important compatibility issues as they relate to botanical, microbial and organic materials that are in current practice.

Click here to register!

The Farwest Show is coming up again! The biggest green industry show in the west, it will be held August 22-24th, 2018, at the Oregon Convention Center. This year Sound Horticulture has moved to a more central location at booth #17027! We really hope that a wide assortment of our growers can take time to attend this important event. We'll have some beautiful items to send with you back to your operations - a really nice poster and other surprises.

Please come and visit with us during the show! You'll gain so much from walking the show floor and attending some of the educational seminars. Thanks, and see you there!

Click here to register!

Sound Horticulture’s resident expert Alison Kutz sits down with John Friel from Emerald Coast to talk about the natural solutions and biocontrols available for every garden enthusiast keen on keeping their plants happy and healthy.

 Take a look here and learn a little more about the bugs we love!