Troubleshooting for Horticultural Professionals I

Troubleshooting is a critical skill for all horticultural professionals to develop. The following is a guide on how to troubleshoot.

DIAGNOSING PLANT PROBLEMS FOR HORTICULTURAL PROFESSIONALS

HOW TO TROUBLESHOOT

Troubleshooting is the art of examining a series of clues, establishing the facts, and arriving at a solution. To be successful, the troubleshooter must begin with an open mind and learn to investigate ALL the possibilities. Jumping to conclusions is the bane of successful troubleshooting. Don't assume that the current problem is the same as the last, regardless of how similar it is. Don't let anyone lead you to erroneous conclusions. If you're not sure about some aspect of the problem, bring in an expert(s) to help. Troubleshooting is detective work. Follow a set of clues to a logical conclusion. Often detective work is eliminating possibilities until only one is left. Along the way, there may be dead ends, false information, hard facts, and circumstantial evidence. To discover and organize the clues, use the following as guidelines.

1) Be prepared.

You will need a good set of references to help interpret the data gathered. References include books, pictures, internet resources, university and commercial fact sheets, compendia, identification keys, diagnostic aids, and experts. Experts include nurserymen and plant growers, commercial horticultural company technical representatives, horticultural suppliers and salespersons, University extension professionals (agents and/or specialists), professors, and horticultural consultants. Also consider other professionals in the horticultural field with many years of experience.

2) Carry sampling tools with you.

A number of items can be of use in troubleshooting. These include, but are not limited to, a sharp knife, soil probe, magnifying lens, and plastic bags (pint, quart, and trash bag size are often needed). Don't use paper bags. Also needed are a plastic bucket (galvanized metal can contaminate soil samples with metals), sweep net and shake cloth, small plastic jars for insects, trowel or small shovel, measuring tapes, a camera (digital or film) for documenting your findings or patterns or symptoms, and a cooler to protect samples from heat damage. Always use good sampling procedures and techniques. When needed, obtain comparison samples: ­good versus bad areas, diseased versus healthy. Sampling can confirm or eliminate possible causes of the problem. Incorrect sampling techniques can either fail to confirm your diagnosis or lead you to the wrong diagnosis.

3) Go to the site with an open mind and investigate all possibilities.

Prepare yourself mentally for the challenge. Refresh your memory. Glance through your reference materials before going to the field. Take the appropriate reference material with you. Don't be afraid to use the materials in front of clients.

4) Where to start.

To be successful and to prevent important clues from being overlooked, you need to follow a systematic procedure. Start by looking at the whole site(s) to determine if there is a pattern to the problem. Ask yourself the following questions: Has the problem occurred before? Is it spreading? Are both weeds and plants affected? (Answering these questions can indicate if the cause is biotic or abiotic.) Does the problem intensity vary? Are affected plants on only one soil type or in a specific area? Are there defined borders to the problem? Look at the surroundings; the answer may be there. Are there any geographic features of importance? Are there man made or physical features of importance (buildings, pavement, walls, etc.). From which direction do prevailing winds come? Is there potential for salt spray from nearby water bodies? What is the water drainage pattern? How does air drain and are there frost pockets? Are there border effects from woodlands or roadways? Are plants in or near woods, vacant lots or in surrounding properties affected? Have nearby properties been sprayed? The answer to these last questions can help you determine if there was a drift problem or adverse environmental conditions. Where the problem occurs, the percentage of plants affected and pattern can aid you in determining if a problem is man-made, physical, chemical, physiological, biological, environmental, or a combination of factors.

5) Gather a complete history.

Ask the client (property manager, home owner, business owner, etc.) about cultural practices. Record previous land disturbance (new driveway, sewer construction, grade changes, etc.), previous plantings, pesticide application history (especially herbicides), lime application, fertilizer application, soil amendments used, snow or ice removal salts used, turf or landscape plant installation procedures, source of planting material, (nursery, greenhouse, seed supplier), plant or seed handling, irrigation and watering practices, mulching practices, and any changes made on the property.

Check pesticide and fertilizer application rates, when practices were done, techniques used, and who did the application. Note when symptoms first appeared. If a chemical was applied find out from the applicator what chemical was last sprayed using that piece of equipment? The site history information will often lead you to the answer or indicate what patterns to look for and what laboratory tests are needed.

Construction, land leveling, topsoil movement, mixing topsoil with subsoil, digging, clearing brush and tree removal (root removal), acid mulch, and non-uniform soil spreading can create soil problems (nutrients, pH, compaction, drainage). Compare past soil tests and nutrient and lime recommendations for the property with what was actually applied and look for trends. Investigate past turf or landscape plant performance for clues. Was the soil worked wet? What kinds of equipment were used? How much traffic was there over the site? Check equipment for potential problems.

Timing and location are important clues. When was the area planted and under what conditions? Where did they start planting a turf area? Where did they start applying pesticides, fertilizers, or soil amendments? Find out on which part of the property they started, what direction they traveled, and on which side of the property they started. Have they done any practices in a different direction?

6) Getting information from clients

If answers to your questions don’t match what you see at the property, you may need to rephrase some of your questions. Sometimes questions can't be answered if the property is new to the client or if the client keeps poor records. You may find it to your advantage to encourage clients to start or improve record keeping. Not only is record keeping important from a legal standpoint, but it can help solve problems quickly and efficiently.

Be diplomatic. Some information can be hard to collect or be embarrassing to your client. Often, the client is upset and defensive if asked a lot of questions. You may need to use a neutral third party or one of your experts to obtain the needed information without a confrontation.
Keep in mind the proliferation of new terminology, new product names (chemicals, fertilizers, etc.), and horticultural terminology. You may have to rephrase questions if you use too much jargon. For example, many people think only of insecticides and fungicides when the term pesticide is used. Weed killers (herbicides) are pesticides too.

7) Environmental data collection.

Find out the weather conditions at the time of critical events: planting, seed germination (for turf), bud break, leaf out, flowering, rapid growth phase, etc. Consider environmental stresses at the site: heat, drought, flooding, cold, etc. Record any information on storm events. If pesticides were applied, gather information on weather conditions during application.
What weather conditions has the property been subjected to in the last few weeks?, for the last year? Ask for rainfall data (and irrigation information). Wind, snow, ice, hail, and temperature are factors that can have a negative impact on plants, depending on timing and correlation with cultural operations. Last year's weather conditions and stresses can impact plant performance this year.

8) Recognize diagnostic versus non-diagnostic symptoms.

As an example, consider a broadleaf evergreen shrub that has developed an abnormal yellow color on the leaves on one branch. This color change is NOT diagnostic by itself. The limb may be a variegated genetic sport, the yellowing may be an initial indication of nutrient deficiencies, it could be due to damage to the stem (physical, canker disease or insect), it could be due to a disease that affects the vascular system or a virus disease, it could be due to damage to one part of the root system, it may be reaction to a chemical, or it may be reaction to a particular environmental stress such as winter injury.

To diagnose the problem, correctly identify diagnostic plant symptoms. In this case symptoms might include stem feeding, a stem canker, physical stem damage, vascular staining, root pruning (insect, critter, human, etc.), poorly drained soil, low nitrogen in tissue tests, positive test for a virus disease, evidence of compaction, evidence of winter injury (that limb was on the north side and stayed iced longer than the rest of the plant), evidence that glyphosate herbicide touched that branch (worker admitting that when wick applying Roundup, he accidentally contacted leaves on that branch) and so forth.

If more than one species are in the same location, are both showing the same symptoms or damage? If not, why? Note the stage of growth when symptoms first became evident. Many diseases occur only at certain growth stages. Distinguish between primary and secondary stresses. Primary stress often brings on a disease response.

Information from a UD cooperative extension factsheet originally written for agricultural crop advisors by Bob Mulrooney and Derby Walker and then modified for horticultural industry professionals by Gordon Johnson.