Irrigation is essential for container production and is typically applied at least once daily during the peak growing season. Scheduling irrigation to avoid both over- and under-irrigation will improve productivity and keep nutrients in place. Under-irrigating plants can result in reduced growth, a longer production period, increased pest pressure on weakened plants, and plant death from desiccation. Since the visible symptoms of under-irrigating are quickly apparent (wilting, desiccation, death), irrigators tend to err on the side of over-irrigating. However, the consequences of over-irrigating are just as detrimental. Over-irrigation can cause reduced growth, a longer production period, increased pest pressure, poor plant quality and even death. Over-irrigation in combination with heavy fertilization can cause overly vigorous plants, also reducing plant quality and often resulting in higher pest pressure on the lush growth.

While under-irrigating cause inadequate water uptake due to a lack of availability, over-irrigation can cause inadequate water uptake due to anaerobic conditions resulting in loss of proper root function, although this is rare.

More commonly over-irrigation leaches nutrients from containers thus affecting plant nutrition, delaying flowering and reducing plant growth and quality. If irrigation water has high alkalinity, as many groundwater sources do, over-irrigating can further exacerbate nutrition problems by increasing substrate pH above the proper range for nutrient availability.

Over-irrigation combined with heavy fertilization to counteract high leaching can lead to even greater problems. Leached nutrients are not only a waste of money but can result in significant environmental problems that increase the probability of regulatory action. Eutrophication is the proliferation of biological organisms in aquatic systems due to excess nutrients, particularly phosphorus and nitrogen, which can cause serious economic and environmental damage. For example, periodically over the past decade toxic algal blooms have negatively affected the drinking water of nearly half a million people who rely on Lake Erie for their water source.

Water is highly undervalued in most areas of the U.S. but that is quickly changing. Over-irrigation wastes water, often relatively high quality water. Although some areas of the U.S. pay a substantial price for irrigation water, the cost of water for most irrigators is the cost to pump it from its source. Low cost is another factor that makes it easy to over-irrigate, however, there are hidden costs to water. Over-irrigation can increase fertilizer costs, although this is often minimal. Most importantly over-irrigation can result in a longer production cycle and all of the costs associated with growing the same crop over a longer period such as more labor, more pesticides, more fertilizer, land costs (fewer crop turns per year), interest, and longer time for return on investment.

Drilling down

Some important considerations to keep in mind when implementing leaner irrigation practices are the source water quality (especially soluble salts and alkalinity), substrate properties, and local rainfall patterns. Routine monitoring of substrate electrical conductivity (EC) for soluble salts and pH (as an indicator of the effect of water alkalinity) using methods such as the Pour-Thru method (Link 1) is essential when using lean irrigation practices. Water with high soluble salts may require periodic leaching if EC exceeds recommended values of 0.5 to 1.5 dSiemens/m (mmhos/cm). However, there is no need to continuously leach salts (fertilizers) from nursery crops, at least in the eastern U.S., unless there is a problem with high salts in the irrigation water. Relatively frequent rainfall during the production season will usually cause sufficient leaching of outdoor-grown container plants. If ECs are consistently high and water does not have high soluble salts it is possible that the fertilizer rate is too high, consider saving some money by backing down on fertilizer rates. Water with high alkalinity will slowly increase the pH of container substrates, possibly above recommended ranges of pH 4.7 to 6.5, depending on the crop and substrate, resulting in the need to apply sulfur compounds or acid-forming fertilizers to reduce substrate pH. In this case irrigating less, if possible, reduces the problem.

It is important to know how water is held in container substrates when deciding how much irrigation water to apply. Some important terms are:

• Substrate Volumetric Moisture Content (SVMC): the amount of water in a container based on volume of water divided by the volume of substrate.
• Container Capacity (CC): the maximum amount of water a container substrate will hold after gravitational drainage.

1. Typically 45 – 60% SVMC

• Unavailable Water (UAW): water that is tightly bound to the substrate and cannot be taken up by a plant.

1. Typically 25 – 35%

• Available Water (AW): the amount of water that can be taken up by a plant.

1. = Container Capacity – Unavailable Water

• Readily Available Water (RAW): the amount of water that can be easily taken up by a plant.

1. Typically the first 10-15% of water below container capacity

• Permanent Wilting Point: the point where a plant has extracted all of the available water and is not able to regain turgor.

These terms are usually expressed as a percent and are calculated as the volume of water in the substrate divided by the volume of the substrate times 100, more on how to determine that later.

It is good to know how much AW is in a container so that you don’t over-irrigate. Irrigating more than the AW will cause leaching because the container cannot hold more water than this under normal circumstances. To calculate how much AW a container can hold is pretty straightforward if you know the actual volume (not trade size) of the empty container (usually provided by the manufacturer), the percent moisture at container capacity and the percent unavailable water. The latter two values can be provided by a good substrate supplier or from a substrate analysis by a substrate/soil testing lab. The available water is the difference between these two percentages. It is easy to convert this to irrigation rate drip or spray stake emitters: multiply the AW times the container volume and divide that by the emitter application rate. For example, with a AW = 25% for a 3 gallon container and emitter application rate of 2 gallons per hour:

• (0.25 x 3 gal)/(2 gal per hour / 60 min per hour) = 22.5 minute run time

If you’re using overhead:

• acre-inch to apply = gallons AW x 231 / pr2
• acre-inch to apply = (0.25 x 3) x 231 / (3.14159 x 5.52) = 1.82
• 231 is the constant to convert gallons to cubic inches, 5.5 is the radius in inches of the 3-gallon pots we use.
• Multiply acre-inch by 27,154 to determine the gallons per acre.

It should be obvious that these values are too high for irrigating 3-gallon pots.

We want to avoid not just the permanent wilting point but wilting as well, so we need to irrigate somewhere in the RAW range. RAW differs by plant species and substrate properties. Fortunately we don’t want to come close to using all of the RAW either. All water in a substrate is not equally available to plants. As water is removed from a substrate the remaining water becomes more and more difficult for the plant to extract. This is a function of the type of substrate and the plant. A good target is to irrigate somewhere between 5 and 10 percent below CC. Calculating how much water to add to replace 5 or 10 percent water loss below CC uses the same equations as above. For example, a 3-gallon container allowed to dry to 7 percent below CC needs 0.21 gallons (0.07 x 3). For a drip or spray stake emitter with a 2 gallon per hour application rate you need to run for 7 minutes to replace 0.21 gallons: 0.21 / (2 / 60). If you’re using overhead:

• acre-inch to apply = gallons to replace x 231 / pr2
• acre-inch = 0.21 x 231 / (3.14159 x 5.52)
• acre-inch = 0.51

The amount of irrigation needed to replenish AW and 10 and 5 percent water loss for various container sizes with a typical nursery substrate is shown in Table 1. In this example, substrate CC is 43 percent SVMC, UW of 18 percent, making AW 25 percent. Obviously irrigating to replace all of the AW is excessive, even the most extravagant irrigator will question irrigating #1 containers with 1.8 acre-inch of water. Irrigating daily at 5 to 10 percent below CC results in rates similar to those we have found over many years of research (links 2,3,4) for plant daily water use for a range of species with different watering needs from very high to low (Figure 1). Remember that these calculations do not take into account irrigation system distribution uniformity (DU). See links 5 and 6 for methods to determine DU. Divide the calculated irrigation rate by the DU for your irrigation system to determine the actual rate to apply. When using these rates you might be at a zero leaching fraction or possibly under-irrigating depending on the species. We have shown that plants can tolerate limited regular deficit irrigations with no detriment in growth as long as they are brought back to container capacity every second or third day. However, this should be done by skillful irrigation managers who are willing to monitor production systems closely.

Improving water management

Closer attention to irrigation practices will become more important as competition for water continues to increase. Additionally, the consequences of over-irrigation and runoff affecting surrounding water resources will be of greater importance. Link 7 has many additional resources to improve water management. So far we’ve only discussed how much water a substrate can hold and how much to replenish at various depletion levels but not how quickly plants use water. A better understanding of how to determine plant water use will allow irrigation scheduling to be based on the plants rather than a set volume of water. There are several methods to determine how much water a plant has used in a day or a certain time period. It can be done by weight, by determining leaching fraction or using substrate moisture sensors. These will be discussed in an article next month.

R. Thomas Fernandez is a professor in the Michigan State University Department of Horticulture, fernan15@msu.edu

The European red mite is a pest of many crops and ornamentals. It is most commonly a problem on fruit trees like apple, pear, plum, prune and cherry trees, but other hosts include rose, black locust, elm, hawthorn, privet, lilac, chestnut, and alder buckthorn.

In the U.S., it was first recorded in Oregon in 1911 and has since become common throughout the U.S. and Canada. European red mite has a long history of developing resistance to miticides. As a result, there has been much work on biological control, with many instances of success.

When choosing a miticide, in addition to its efficacy, growers should check how selective it is toward beneficial arthropods, especially predatory mites. Use of a selective miticide greatly enhances the chance of establishing biological control, which should be the ultimate aim of any mite control action.

Not so long ago, most people in the workplace received feedback once-a-year during a performance review. An employee didn’t expect a development plan, a career track, or anyone to take an interest in his or her professional growth. That responsibility was often a solo activity. In fact, as recently as a couple of decades ago, there wasn’t a great deal of help on the road to career success, and most people didn’t complain. It simply was what it was.

But times change, and norms evolve. The practice of once-a-year feedback is fast becoming an anachronism and as out of place in the modern office as the fashions people once wore when holding those annual reviews.

The reason the average worker has evolved to expect a steady diet of attention and conversation is debatable and perhaps worth scholarly inquiry. In the meantime, however, a demand for dialog exists and must be answered.

So, why should managers take action, what does it take to establish and maintain an ongoing give-and-take, and how can managers balance the constant conversation with their own workplace responsibilities?

How to establish and maintain a dialog

Once you’ve bought into the notion that routine conversation is a must, the next step is knowing how to guide interactions.

Take an interest. Very little builds engagement as well as a manager who seems to genuinely care for people, promotes their success, and has the ability to develop them. This is not an annual affair. Rather, you’ve got to have a range of formal and informal conversations throughout the year. To get started, ask questions, and pay attention to the answers.

There is no limit to the questions you could ask. The key is showing a sincere interest in the answers, withholding judgement about what you’re told, and taking action when you can.

Be observant. As a manager, your job is to focus on the work that gets done and how it gets done. When you pay attention and are specific with your feedback, you show you’ve spent time to notice what’s working and where opportunities exist. In other words, it’s important to communicate to people they matter to you.

Finding the time for planned dialog

There is no clock fairy or magic solution to time management and fitting feedback and development conversations into a regular workload. It’s an effort that requires discipline. To ensure planned dialog happens, you need to put formal meetings on a calendar, schedule them at regular intervals, show up on time, and put the smartphone away.

The payoff

While increased levels of informal feedback and scheduled conversation can seem overwhelming at first, the more often a manager engages, the easier it is, the franker the discussions become, and the greater the understanding between the employee and the manager grows.

With whom should you be having conversations?

One of my favorite workplace comics is a Dilbert cartoon where Wally asks the boss, “When will my raise be effective?” The boss answers, “The same time you are.” Poor Wally. Maybe he just doesn’t understand his job duties. How can Wally be effective if he doesn’t know what is required of his job? Answer: He can’t. How can Wally get a grip on his job duties? Answer: A job description.

Accurate and detailed job descriptions are a vital part of an organization’s HR infrastructure. As companies develop, roles become refined, duties are more defined, and the organization obtains a better idea of the background skills, abilities, and experiences necessary for success in the position. All of this should be captured in the job description.

Job descriptions play a vital role in many HR-related practices and, when properly written, can help bolster the company’s position when faced with work-related injuries, discrimination allegations, overtime exemption questions and other serious matters.

Comprehensive and well-worded job descriptions affect several key HR practices, such as:

• Medical leaves, FMLA, safety, and workers’ compensation – Any time an employee is injured on the job, requests a medical leave, or encounters a medical condition that could impact job duties, the job description can be used by the physician to help determine any limitations or work-related restrictions. Often, these decisions are based on a conversation between the employee and the physician, with little or no input from the company. Physical and mental demands may be under- or overstated by the employee, leading to inaccurate work releases that either prolong the medical leave or raise the risk of reinjury. Job descriptions that accurately describe the physical and mental requirements for the position reduce liabilities by eliminating the potential for erroneous assessments of work limitations.
• Compensation plans and rates of pay – Job descriptions that clearly state the essential job duties and background qualifications for a position (e.g., required or preferred education level and prior experience, skills and abilities) are necessary to obtain market rates for comparable positions in compensation surveys. They are also essential to conduct meaningful point-factor analyses for compensation plans. Without accurate and sufficiently detailed job descriptions, it is difficult to determine an appropriate pay rate and to ensure internal equity.
• Department of Labor (DOL) and EEOC compliance – Job descriptions that accurately reflect and define the exempt nature of a given position can help the company meet the DOL’s burden of proof pertaining to overtime provisions. Additionally, job descriptions can help defend the company’s position related to hiring the most qualified candidate, equal pay, or other discrimination allegations related to promotions, transfers, and terminations.
• Recruiting and Hiring – Comprehensive job descriptions can be used to develop creative, accurate job postings. Detailed job descriptions that include the education, background skills, abilities, knowledge, and prior experience required for the position also help managers develop meaningful interview questions based on job-related criteria. This, in turn, can impact the quality of the hiring decision and the candidate selected.
• Americans with Disabilities Act (ADA) compliance – The Americans with Disabilities Act protects qualified individuals with disabilities who can perform essential job functions with or without a reasonable accommodation. Job descriptions that accurately outline the essential job duties, specific qualifications, and physical and mental requirements for the position help managers make accurate decisions related to a candidate’s qualification for a position, his or her ability to perform essential job functions, and the potential for making reasonable accommodations before or after hire.
• Training and development – Comprehensive job descriptions can be used as training tools to guide new employees. They can also be used as a baseline for managers when they evaluate performance, identify opportunities for improvement, and refocus employees. Additionally, job descriptions can be used to enhance safety training and awareness.
• Organizational development – As companies grow, updated job descriptions provide direction to hiring managers and are useful guides to assess productivity, spans of control, efficiency, staffing levels and alternatives for reporting relationships.

To be effective, job descriptions should be accurately worded, legally compliant, detailed enough to provide a meaningful explanation of the essential job duties, and written in a fashion that supports the organization’s culture, mission and philosophy. Just like hiring, there is an art and a science to writing effective job descriptions.

The best job descriptions do not describe how the job is done; nor do they define the performance standard required. The best job descriptions focus on essential job functions by clearly and concisely describing job duties, using a verb to start each sentence (e.g., “monitor,” “complete,” “oversee,” “coordinate” or “prepare”). They also include the following components: position summary (overall purpose of the position); minimum education or certification level required and background skills, abilities, and qualifications (specify if required or preferred); essential job duties; physical and mental demands; typical work environment; equipment used; reporting relationships; and a disclaimer pertaining to employment at will.

Here’s an example of verbiage outlining the background skills, abilities, and qualifications for portion of an office manager job description:

High school diploma required. College coursework in business or related field preferred. Minimum of three years’ experience in a supervisory administrative position required. Must be able to demonstrate successful track record of running an office, including supervision of employees and knowledge of payroll, accounts payable and receivable, profit/loss, and budgeting. Must be proficient in computer operations, spreadsheet applications, and data entry. High degree of accuracy required. Aptitude for numbers and strong analytical skills required. Must possess integrity and ability to maintain confidentiality. Professional image and ability to communicate with diplomacy and tact required. Must possess ability to operate general office equipment. Must be organized, flexible, friendly, and exhibit a willing-to-please demeanor. Must possess strong written communication and follow-through skills.

Get the idea? Writing job descriptions is time consuming and takes a fair amount of detail, writing ability, and job knowledge. If you’re not comfortable producing job descriptions that will (1) support your business (legally and otherwise), (2) communicate effectively with your employees (or potential employees), and (3) promote your organization’s culture and business objectives, get some help. Otherwise, you could end up with a bunch of “Wallys” at your business.