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Managing Whiteflies and Aphids with MGK’s Botanical Insecticides

Aphids and whiteflies actually have a lot in common. Whiteflies are not actually flies at all. In fact, both aphids and whiteflies are in the order Hemiptera and suborder Sternorrhyncha so they are fairly closely related, as far as insects go, and many of the control techniques work similarly on them. They are similar in size, both soft bodied, and have piercing sucking mouthparts. Some differences are that whiteflies are winged and although aphids are sometimes winged, most often they are not. Whiteflies often are covered in tiny waxy scales giving them that bright white appearance, while aphids are not but come in a variety of colors such as yellow, green, black, and even pink. If you are unsure about whether you have whiteflies or aphids, you can take them to an entomologist for identification.

Aphids and whiteflies seem to be an ever present or at least frequently reoccurring pest that every grower I know has dealt with at one time or another. You are not alone! These tiny yet fierce little creatures can wreak havoc on your plants.

There are many different tactics and options to consider when trying to manage these pests including cultural controls, biological controls, exclusion, and physical removal. For this article we will focus on MGK’s botanical insecticides. Contained in your arsenal of botanical options are EverGreen Pro, PyGanic Specialty, and Azera Gardening. They have some key differences I will discuss below.

Botanical Whitefly and Aphid Control Products:

EverGreen® Pro 60-6 is a botanical product that contains the synthetic synergist piperonyl butoxide (PBO) as well as the botanical active ingredient pyrethrins. The product is 60% PBO and 6% pyrethrins. They work together to create a more effective insecticide for the whiteflies and aphids. The PBO binds to enzymes and prevents them from breaking down the active ingredient inside the insect. This allows the insecticide to have a more powerful and lethal effect on the insects without adding more insecticide.

PyGanic® Specialty is an OMRI listed product containing 5% pyrethrins. If you want or need an organically certified product for professional plant production, then this one will work for you. It has the same active ingredient as EverGreen Pro 60-6, but without the added synthetic synergist.

Azera® Gardening is an OMRI listed combo product containing azadirachtin and pyrethrins. It contains 1.2% azadirachtin and 1.4% pyrethrins. The dual action active ingredients provide different modes of action that can combat potential resistance or delay the development of resistance. Azadirachtin has a little bit longer half-life than pyrethrins in most situations although still breaks down fairly quickly. Not for use on plants being grown for sale.

When picking one of these insecticides, consider them in regards of all the factors that are important to you. Some of those factors could be OMRI listing, multiple modes of action, extra killing power of a synergist, and let’s not forget cost. To effectively consider costs, find the labels and look at how much a finished gallon per 1,000 ft2 will cost at the rate you want to apply and how many total finished gallons that container will make then compare amount of area treated per insecticide container. That will give you a better picture of cost per application rather than comparing concentrates side by side that may have different mix rates.

With all three of these botanical products there is no pre-harvest interval, with a few limited restrictions for things like cotton and rice. Therefore, with EverGreen Pro 60-6 or PyGanic Specialty you can spray in the evening and ship or sell the plants or crop the next morning. With Azera Gardening there is also no pre-harvest interval but it is not for use on plants being grown for sale. Remember to read the label carefully for the product you choose to make sure you are following all label instructions.

How and When to Apply the Products:

When do you need to apply these products? Spray as soon as you detect an infestation. It is best to nip the pest problem in the bud so to speak… or maybe literally, Ha! Seriously though don’t let the problem get out of hand. It is much easier to deal with a new infestation on a few plants (hot spots) as opposed to waiting until all plants in a planting have high pest numbers with serious damage and crop losses.

When you do find a problem and decide to spray, coverage is key. Make sure to get all the surfaces where pests may be resting or harboring. Undersides of the leaves are especially important. These insecticides are contact insecticides and they have to contact the insect in order to be effective. Multiple treatments may be necessary to get all the insects. Whiteflies and aphids are tiny and whiteflies especially are mobile and it is difficult to get all of them on the first spray. Spraying in the evening when there is less UV light can slightly extend the period of efficacy of pyrethrins. Night spraying also avoids getting insecticide on most pollinators that visit flowers during daylight.

When should you not apply these products? Do not apply them as a preventative when no pests are present because it is a waste of product. You may also quickly reach the maximum numbers of sprays allowed on a crop per season and not be able to use the product later when pests appear. Most if not all botanical based insecticides have very short period of efficacy and most insects are killed after getting covered with insecticide or on contact. Because UV light breaks them down so quickly you cannot use them to kill insects that may arrive after a spray. Pyrethrins have about an 11 hour half-life outside in direct sun. UV light is the quickest way to break down the product, but other break down mechanisms include microbes and oxidation.

Monitoring for pests is one of the most important things you can do to maintain the health of your plants. If you don’t know there is a problem, you certainly can’t do anything about it. So make a weekly schedule and look for aphids and whiteflies on yellow sticky cards (1 card per 1,000 ft2 of bench) and also randomly inspect for these pests on all parts of the more susceptible plant varieties, new plant cuttings and weeds in all parts of the greenhouse, especially by fans and doors. Mark each pest hotspot with flagging for future insecticide treatment and/or inspection. Also, implement various sanitation practices to minimize pests that may develop on weeds under benches, around greenhouse exteriors and mulch on floor.

Sandra Sleezer

MGK – Technical Service Coordinator

January 12, 2018

Acknowledgements: Sandra would like to thank Dr. Donn Johnson, professor of entomology at the University of Arkansas, for his contributions in editing and improving this article to the benefit of those who will read it.

© 2018, Mycorrhizal Applications LLC


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Endomycorrhizal Benefits for Professional Growers and Horticulturists

Endomycorrhizal fungi (also known as arbuscular mycorrhizal fungi, or AMF) are beneficial microscopic organisms that live in the soil and have evolved a symbiotic relationship with approximately 85% of the world’s plant species over the past several hundred million years.  These fungi predate the evolution of terrestrial plants, and it was the partnership with mycorrhizal fungi that allowed plants to begin to colonize dry land and create life on Earth as we know it.

How does this relationship between beneficial fungus and plants work?

The AMF symbiotic relationship centers on the plant’s ability to produce carbohydrates through photosynthesis and share some of these sugars with the fungus in return for otherwise unavailable water and nutrients that are sourced from the soil or growing media by the extensive network of mycelial hyphae produced by the fungus.  It’s a two-way relationship of sharing resources between two species, thus a classic symbiotic mutualism.  The endomycorrhizal fungi rely on the plant, and the plant’s performance and survival are enhanced by the fungus.

How is this symbiotic relationship established?

Endomycorrhizal fungi can colonize plants from three main sources of inoculum: spores, colonized root fragments, and vegetative hyphae.  Collectively, these inoculants are called “propagules,” and this is the standard unit of measure that is listed on most commercially available mycorrhizal products.

To colonize plant roots, these propagules must be present in the substrate and in close proximity to actively growing roots of a compatible plant.  The growing root tips emit root exudates as they push through the substrate, which signal the fungi to colonize the roots and establish the symbiosis.  Once the roots are colonized, then the process is self-sustaining as the vegetative bodies of the AMF ( the fungal mycelium) continue to grow with the plant’s root system and additional spores and hyphae are produced.

To inoculate plants grown professionally or in a home garden, AMF propagules can be incorporated into the substrate prior to or during planting or they can be top-dressed on the surface and watered into a porous substrate.  They can also be applied as a dip or slurry at the time of sticking a cutting, seeding, or at the time of transplanting.  The propagules can also be applied as a drench to the soil and watered-in, applied to the outer surface of the rootball before transplanting, or used in transplant hole and backfill soil.

How can professional growers utilize this symbiosis?

The application rates for endomycorrhizal fungi are based upon the number of propagules per volume of soil for container-grown plants and per area of coverage for turf and landscape plantings.  Therefore, large containers will require more propagules than smaller containers.  For a professional grower, it is more cost-effective to treat plants early in the crop cycle when they are growing in smaller volumes of soil, and will require fewer propagules per plant to achieve colonization.  Germination of the spores occurs relatively quickly after contact with growing roots, but full colonization of the roots can take several weeks.  Plants will reap the full benefits of the colonization within 6-8 weeks after application.  Some plant species will demonstrate the benefits of mycorrhizal colonization sooner than others.

The mycorrhizal fungi colonize the developing roots by growing into the plant’s root cells to obtain carbohydrates and simple sugars (food).  The tiny fungal mycelial threads grow throughout the available soil volume and effectively “mine” the soil for water and nutrients that the plant cannot access or absorb on its own.  The enhanced water uptake helps the plant to resist drought conditions and ensures faster plant response if its roots are damaged by adverse conditions (drought, water-logged conditions, high salts or high soil temperatures).  The mycelium also secretes organic compounds that help solubilize nitrogen, phosphorus and other macro- and micronutrients from the substrate.  These nutrients are actively transported by the fungus to the plant to produce proteins and other components needed for vigorous growth and development.

How it Works Diagram

Why do horticulturists and professional growers need mycorrhizal fungi?

With traditional input-intensive growing protocols, nursery or greenhouse grown plants are produced under optimum conditions and may be able to perform sufficiently in the short-term, without the assistance from mycorrhizal fungi.  However, water restrictions in production and landscapes will encourage growers and consumers to be water-wise and utilize mycorrhizae as part of our water management programs and promotions.  Trials have demonstrated that the use of mycorrhizae can reduce water requirements significantly by increasing the plant’s ability to utilize and store water through the AMF mycelial network of hyphae.  Consequently, retailers and growers have realized reduce shrinkage due to drought and stressful conditions in the retail chain.

There is additional pressure to reduce the runoff of nutrients, especially nitrogen and phosphorus, from nurseries, greenhouses, and landscapes.  Both of these essential plant nutrients are accessed and delivered to the plants by mycorrhizal fungi, and in many instances these inputs can be reduced significantly by utilizing AMF without a noticeable reduction in crop time, appearance, or performance.

Excess water usage results in more runoff and excess fertilization results in more pollution of the environment.  Many conscientious growers welcome beneficial biological solutions like mycorrhizal fungi to help reduce these environmentally harmful growing techniques, and this type of technology is becoming a major part of the toolkit to increase the overall environmental sustainability of the horticulture industry in the long run.

Are professional endomycorrhizal products available for greenhouse and nursery growers?

Mycorrhizal Applications, the leading producer of mycorrhizal propagules in the US, produces a suite of professional products that make it easy for growers to trial mycorrhizae and to incorporate it into their production programs.  Their flagship “MycoApply” endomycorrhizal inoculum products contain four different Glomus species of AMF for optimal diversity and performance under most growing conditions and crops.  These flagship endomycorrhizal inoculant products are MycoApply Endo and MycoApply Ultrafine Endo.  MycoApply Endo is a granular formulation containing 60,000 AMF propagules per pound and is ideal for soil incorporation, as the granular consistency blends evenly with growing media and soils.  MycoApply Ultrafine Endo is a suspendable powder containing 130,000 AMF propagules per pound which can be soil-incorporated or prepared as a liquid suspension for use as a soil drench or plug tray dip.  Whether incorporating the granular product into your media or drenching with the suspendable powder formulation, it is important to get the propagules in the root zone as soon as possible and as early in the crop cycle as possible.

 

MycoApply Endo & MycoApply Ultrafine Endo

Where can I learn more?

Plants and mycorrhizal fungi have had a long-term relationship for over 400 million years and we are just beginning to understand this relationship better and are now employing this symbiotic mutualism in professional horticulture.  You can learn more about mycorrhizae by going to Mycorrhizal Applications’ website (http://mycorrhizae.com/) or by contacting Mycorrhizal Applications directly at 1 (866) 476-7800.  Resources and literature such as Fungicide Interactions with Mycorrhizal Fungi, and the Mycorrhizal Status of Plant Families and Genera are available through their website or by contacting them directly, in order to help you determine how to include mycorrhizal fungi most effectively into your professional growing protocols.  MycoApply products are also available through many horticultural distributors throughout North America.

Hugh A. Poole, Ph. D.

Horticultural Technical Consultant

September 12, 2017

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