Registration for our 2024 Green School has Begun!

UMass Extension’s Green School is a comprehensive 60+ hour certificate short course that offers fundamental horticultural training in a compact time frame.

Who Should Attend? Professional practitioners such as landscapers, lawn care providers, nursery operators, sports field managers, public and private grounds managers, DPW, professional gardeners, landscape and garden designers, and others in the green industries. Both experienced individuals, as well as those aspiring to be, will benefit from this course.

Where? Entirely virtual in 2024, taught by UMass Extension Specialists, UMass faculty, and distinguished guest instructors. 

When? Tuesday, Wednesday and Thursday afternoons 1:00 to 4:30 pm from 10/29/2024 thru 12/19/2024.  

How? The curriculum emphasizes a systems-based approach to plant and land care based on current research and is built on a framework of Best Management Practices (BMPs) and Integrated Pest Management (IPM). 

Choose from two specialty tracks: 

• Landscape Management

• Turf Management 

For complete information, detailed schedules and registration options, go to https://ag.umass.edu/greenschool

Why Choose Green School? 

• A robust alternative or a stepping stone to a more involved degree program.

• Convenient yet rigorous remote learning from the comfort of your home or office.

• In-depth, research-based training for skills that are in high demand, and are applicable to active and engaging outdoor work.

• Two educational track options to fit your personal goals.

• Structured interaction with University educators and researchers.

• Competitive fees and tuition assistance options.

• An established program with a 30+ year history and a certificate that carries weight in the industry.

Move your career or business forward, and achieve better results with a smaller overall impact!

Are Microbial Probiotics Worth Adding to Your Soil?

• Other than rhizobia for legumes, soil inoculants aren't yet reliable soil amendments.

• Use reduced tillage, compost, and ground covers to encourage the growth of existing beneficial bacteria and fungi.

Bacteria and fungi play a large role in the health and productivity of soil. The plants we grow need these microbes for soil fertility, protection from disease and other stresses, and good soil structure. Unfortunately, we all know about microbes that compete with plants for soil nutrients and cause plant disease. This means that having the "right" microbes is important for plant and soil health.

But how do you know if you have the right ones? And enough of them? While a lot of pathogens cause recognizable symptoms, sometimes plants just don't look "great." In these cases, it's hard to know if a soil microbiological imbalance could be part of the reason. However, this topic is different than soil fertility, where there are reliable and accessible soil tests which easily identify issues and solutions. Unfortunately, we don't have reliable tests for soil microbiology yet. In the meantime, growers should follow best practices to encourage healthy bacterial and fungal ecosystems in the soil. These are tried and true growing methods, but sometimes it seems like maybe that's not enough and many microbial probiotics or soil inoculants are available to supplement the organisms already in your soil.

So does it make sense to add beneficial bacteria and fungi to your plantings? The short answer is "no." The slightly longer answer is "the effects of soil probiotics usually aren't reliable enough to bother with." Of course, that's still a pretty short answer! So let's dig into it a little more.

What beneficial microbes do: Bacteria and fungi are the core of the soil ecosystem. Without them, the soil would not be fertile or have structural integrity. They can make phosphorus and nitrogen available, alleviate drought and salt stress, reduce pest and disease pressure, generally promote plant growth, and reduce greenhouse gas emissions. Despite this diversity of function, soil probiotics fall into only three main types: mycorrhizal fungi, "plant growth promoters," and rhizobia.

Mycorrhizae: Their name means "fungus root" for a reason. These symbiotic fungi intertwine with plant roots and vastly expand the effective size of the root system. Mycorrhizae are particularly good at collecting phosphorus from minerals and trade it and water to the plants in exchange for photosynthetic carbon.

Plant Growth Promoters: This is a catch-all group which includes some members of many groups like Trichoderma, Pseudomonas, and Bacillus. Individual types of bacteria can do many different things in laboratory and greenhouse research trials and have improved plant performance by stimulating the plants' immune systems, making phosphorus available for plants, and reducing environmental stress in some controlled conditions.

Rhizobia: Leguminous plants (like clover, beans, indigo, and wisteria) create root nodules for rhizobia bacteria. In these nodules, the rhizobia take nitrogen out of the air and give it to the plants in exchange for carbon resources. This means that healthy legumes generally need no added nitrogen fertilizer. Most legumes require specific strains of rhizobia to perform at their best.

All of these organisms are great for plants in the right circumstances! All of them have the potential to make useful additions to garden and landscape toolkits someday. Unfortunately, while these microbes are starting to show real promise in lab and greenhouse studies, most of them aren't yet performing reliably in real-world settings. Rhizobia are the exception that proves the rule. Landscape-scale use of rhizobia has proven to be highly effective as a seed inoculant when the right strains aren't already in a particular soil. While it's not needed for common weedy legumes like red and white clover, adding a rhizobia strain that works with your legume plants is definitely an important seed treatment.

But other than rhizobia, you're better off simply following soil health principles and ignoring the microbial content of potting mixes and soil amendments. More reliable microbial strains and application methods to add mycorrhizae and "plant growth promoter" bacteria to plantings may arrive in coming years. But until then, reducing tillage, adding organic matter like compost and mulch, and using groundcovers to protect the soil are still the best ways to encourage the growth of beneficial bacteria and fungi already in the soil.

Arthur Siller, UMass Extension Soil Health Educator

Trouble Maker of the Month

Surfactants with Landscape and Turf Herbicides

Herbicide performance is the primary goal with any herbicide application. When developing a weed management program for landscape or turf, we should first focus on correctly identifying the target weed and its growth stage. The next step is to determine the herbicide and formulation that will result in the best control. Lastly, focus should be shifted to abiotic factors such as soil moisture and air temperature that might impact overall herbicide performance.

With these initial tasks completed, it is then time to explore whether the addition of a spray surfactant is required to achieve the best herbicide efficacy. Spray application is often considered the weakest link in the herbicide effectiveness from its initial synthesis, testing, product registration, and final use. In other words, you can have a great herbicide, but if you cannot get it into the plant it is of little or no value. Surfactants can strengthen or eliminate this weak link in performance.

A surfactant is a material that is added to a spray solution to modify its physical characteristics and/or to aid the action of an herbicide. The word surfactant is derived from the term “surface-active agent."  Surfactants increase herbicide performance by solubilizing spray materials, reducing surface tension, increasing spreading, improving spray retention, and increasing leaf penetration. While all of these functions are important, the reduction of surface tension rises to the top of the list.

The unit traditionally used to measure surface tension is dyne per centimeter (dynes/cm). The surface tension of distilled water at 25°C (77°F) is 72 dynes/cm. With a surface tension of 72 dynes/cm, a reduction of herbicide activity can be observed as the spray droplets sit on leaf hairs or the leaf surface with minimal leaf surface contact. Surfactants typically reduce surface tension to 20-40 dynes/cm and provide broader leaf contact by increasing leaf contact by spray droplet spread over the leaf surfaces and penetration of hairy leaf surfaces. This increase in spray coverage directly improves herbicide activity and performance. Surfactants used with postemergence herbicide applications increase the amount of herbicide entering the plant and reaching the targeted site of action in the weed.

There are many types of agricultural surfactants used when preparing a spray solution for an herbicide application. The most common types of surfactants used with landscape and turf herbicides are non-ionic (NIS), crop oil concentrate (COC), and methylated or modified seed oil (MSO). The herbicide product label will state if the addition of a surfactant is required. The simple rule is that if the product label calls for a specific surfactant, then that type of surfactant should be used.  If the product label does not call for a surfactant, then one is not needed and should not be added. Different herbicide products require different surfactants. Your pesticide distributor will be able to assist you in the selection of the correct surfactant. An overview of the surfactant type needed with some key landscape and turf herbicides is shown below in Table 1.

Table 1. Surfactant type needed with some landscape and turf herbicides (The information in this table is not meant to replace label instructions.)
Herbicide (active ingredient)	Trade name (example)	Surfactant type	Comment(s)
clethodim	Segment IITM	methylated/modified seed oil (MSO) or crop oil concentrate (COC)	Non-ionic surfactants (NIS) or blends are not recommended as weed control may be unsatisfactory.
fenoxaprop-methyl	Acclaim ExtraTM	specific type not stated	Specific type not stated but label states the addition of a surfactant will improve coverage.
glyphosate	RodeoTM	non-ionic surfactants (NIS)	Nonionic surfactant (NIS) containing 80% or more active ingredient; using this product without surfactant will result in reduced performance.
glyphosate	Round Up ProTM	not required	Surfactant added by manufacturer; consult label of generic glyphosate formulation for surfactant requirements.
halosulfuron	SedgehammerTM and Pro SedgeTM (surfactant type and comments same for both products)	nonionic surfactants (NIS) that contain at least 80 percent active material	Use 0.25-0.5 percent v/v of a nonionic (NIS) surfactant (NIS) at (1-2 quarts per 100 gallons of spray solution) for broadcast applications. For high volume applications, do not exceed 1 quart of surfactant per acre.
mesotrione	TenacityTM	non-ionic surfactants (NIS)	Required for postemergence applications; not required for preemergence applications of this product.
quinclorac	Drive XLR8TM	methylated or modified seed oil (MSO)	Methylated or modified seed oil (MSO) is preferred for postemergence applications; however, if an MSO is not available the use of a crop oil concentrate (COC) or another high-quality surfactant must be used. Required for postemergence applications; not required for preemergence applications of this product.
topramezone	PylexTM	methylated/modified seed oil (MSO) or crop oil concentrate (COC)	Methylated/modified seed oil (MSO) or crop oil concentrate (COC) at 0 5 to 1% volume/volume (v/v) (2 to 4 qt./100 gallons of spray) or 30 ml per 1000 sq. ft. Nonionic surfactants (NIS) or blends are not recommended as they may provide unsatisfactory weed control.

In summary, surfactants are materials that are added to a spray solution to modify its physical characteristics and/or aid the action of an herbicide. Surfactants will increase herbicide performance and provide economic benefits. Remember this simple rule about surfactants; “if the product label calls for a specific surfactant, then that type of surfactant should be used; if the product label does not call for a surfactant, then one is not needed and should not be added."

Randy Prostak, UMass Extension Weed Specialist