Groundwork: "Improved center helps solve plant problems"

Photo provided by BOB SOUVESTRENematodes attack plant roots resulting in poor growth, reduced yield and branch dieback. Late summer is the best time to submit a soil sample to test for suspected nematode populations.

The “Plant Doctor” is in to diagnose and solve your plant health problems at the LSU AgCenter’s new and improved Plant Diagnostic Center.

Plant health problems are caused by a variety of plant pathogens, nematodes, insect pests and mites. Weeds compete with your plants for space, sunlight and nutrients. Adverse environmental conditions also can contribute to plant health problems.

Plant problems caused by different agents may exhibit similar symptoms, or those caused by similar agents may show different symptoms. Before you attempt to correct a problem, you must first determine its cause. That’s where the Plant Diagnostic Center can help.

Services available through the center include plant disease diagnosis (biotic and abiotic causes), insect and mite diagnosis and identification, nematode diagnosis and identification, and weed identification.

The staff of the Plant Diagnostic Center has the training and experience to help you solve your plants’ problems. Before you submit a sample, however, it is suggested you contact your parish LSU AgCenter extension agent. Agents are familiar with many of the common plant problems encountered and can help evaluate the situation.

Accurate and rapid diagnosis at early stages of problem development help you select the best management practices and implement them at the most effective time. The center offers the practical management practices that are tailored just for you to help get rid of the problem for long term. You also receive up-to-date information on use of chemical control methods.

Accurate and rapid diagnosis requires accurate information about the problem, including a detailed description of how it developed.

In addition, a “good,” fresh sample is a must. Remember: the better the sample the more accurate and rapid the diagnosis. Read and follow the sample submission guidelines before submitting samples.

A good sample generally consists of plant materials showing all phases of problem development and includes plant parts with both healthy and affected tissue.

Completely dead leaves, branches and plants or rotten fruit generally are not useful, but they may be included as part of the sample. Plan to collect and submit samples early in the week.

Also, be sure to collect the specimens before applying any chemicals, and submit a generous amount of plant material. Samples without the sample submission form and diagnostic fee may delay the diagnosis.

For plant disease diagnosis:

Plants showing root rot, wilting, yellowing or general decline: Send whole plants, including roots, if practical. Be sure to send plants showing early stages of disease.

Dig them carefully. (Don’t pull up.) Send a sample of soil and feeder roots in a plastic bag and seal the bag to avoid loss of moisture.

Cankers: Select specimens from recent infestations. Send entire cankered portion, if possible, with some of the healthy wood above and below the canker. Branches and twigs that have been dead for several months are useless for identification.

Leaf spots, blights and scorch: For scorch symptoms, send in several footlong affected twigs or branches with leaves attached. Wrap these in dry paper towels and pack in a plastic bag. For spots or blight, wrap 15-20 leaves (showing early and late stages of infestation) in dry paper towels and then pack these in a plastic bag.

Fleshy organs: Do not send fruits and vegetables in advanced stages of decay.

Select fresh specimens showing early symptoms, and wrap these individually in dry paper towels. Do not add extra moisture and pack these in sturdy cardboard boxes. Keep them cool until shipped.

Turf: For turf, take samples (6 inches by 6 inches) from areas with both healthy and diseased grass, generally at the edges of patches.

Again, dig up the grass and include foliage, roots and soil in the sample. Once you collect a sample, be sure to package it so it doesn’t dry out before it reaches us — but don’t add water.

We prefer you place samples in plastic bags rather than paper bags and submit them as soon after you collect them as possible.

For nematode diagnosis and identification: Late summer and fall are the best times to take nematode samples. Nematode samples require at least a pint of soil from approximately 10 spots. Mix soil together and mail the sample in a plastic bag placed inside an LSU AgCenter soil box.

The sample must be accompanied by a nematode assay form with required information. Protect the sample from heat and light.

For insect pests, mite diagnosis and identification: Collect damaged plant parts, such as leaves or twigs and wrap these in dry paper towels and place them in plastic bags. If a root sample is submitted, pack the damaged roots with soil intact in a plastic bag.

Submit insect specimens in glass vials containing ethanol. Label the vials with the collection information — site, host plant, date and collector’s name. Complete the sample submission form for each sample specimen submitted for diagnosis.

For weed identification: Send in the entire plant for identification. Leaves alone may not be sufficient for an accurate identification.

Dig plants carefully. (Don’t pull up.) Wrap roots in a plastic bag and the rest of the plant in dry paper towels, and pack the entire plant in a plastic bag. High-quality images of the plant may aid in identification.

Sample packaging: Do not add water to samples. Follow the packaging guidelines for type of samples explained under different sections.

In addition, pack specimens from different plant species separately. Pack samples in a sturdy cardboard box. Wrap the package in heavy paper. Identify the package with labels both outside and inside, but don’t put an inside label where it may come in contact with moisture.

Place the completed sample submission form and payment in a plastic bag and include it with the sample. The diagnostic fee is $20 per sample for routine diagnosis.

Sample mailing: Be sure to mail packages to arrive on weekdays (Monday through Friday) rather than on the weekend. Ship samples immediately after collecting them, preferably overnight deliveries. Write the correct mailing address on the package.

Address the package to: Plant Diagnostic Center, 302 Life Sciences Building, LSU campus, Baton Rouge, LA 70803. Samples can also be dropped off at the center when visiting the campus. For more information and to download and print necessary forms, visit the website, http://www.lsuagcenter.com/plantdiagnostics.

Got a gardening question? Write to Bob Souvestre, horticulturist with the LSU AgCenter, at Burden Center, 4560 Essen Lane, Baton Rouge, LA 70809, or email to [e-mail], or call Master Gardeners at [phone].