One of the best-kept gardening secrets of the University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources is the Agricultural Diagnostic Service Center. The ADSC conducts analyses and diagnostic tests for ongoing UH-M research, other government agencies, businesses, farms and the gardeners of Hawaii. The ADSC testing can be listed under the general heading of plant disease identification, insect identification, feed and forage analysis and chemical analysis of soil, plant tissue, water and nutrient solutions. The menu of services and their costs can be found on the ADSC website at ctahr.hawaii.edu/site/ADSC.aspx. While 35 analyses are listed, most of us will use only a few of the services. The most widely used services are disease and insect identification, soil pH and extractable nutrients.
The service center, staffed by a group of dedicated individuals, is headquartered on the University of Hawaii at Manoa campus. Award winning diagnostician Brian Bushe heads the Big Island’s Komohana Research and Education Center in Hilo. Bushe was selected for the State of Hawaii Governor’s Award in the category of the best individual state employee for 2009-2010. He handles disease and insect identification for the island and coordinates soil and plant tissue sample delivery to Oahu for analysis.
When submitting a sample, it is very important to collect one representative of the analysis needed. For insect identification, collect multiple insects if possible and different growth stages, if available. Additional information like host plant and where insects are found on the host plant will be beneficial. For plant disease samples, it is best to submit samples that express the disease symptoms but are not fully dead. A common mistake is to submit samples that are dead and beginning to rot. Identification of the primary plant pathogens from rotting plant material is made more difficult, if not impossible, due to the exponential growth of opportunistic organisms. For diseases that cause rot, the best place to identify the causal disease organism is the zone between healthy tissue and the diseased tissue. In this intermediate zone, the disease organism can be isolated without the opportunistic organisms. Sample size should be appropriate and proportional to the sample of the host plant being submitted. A few leaves is a fine sample for a foliar disease, but a section of a tree trunk or roots may be more appropriate when finding out what killed your tree. It’s always a good idea to place your insect or diseased sample in a bag or sealed container to prevent their spread.
For a good soil test, it is important to get a representative sample for the location you wish to evaluate. Divide the plot into fairly uniform soil types. Each soil type will need a separate test to correctly recommend the amount of needed fertilizer. Submit two cups of soil, or about half a quart storage bag. Using a shovel, dig out a section of soil 6 inches deep and place it to the side. Cut a second section about 1 inch thick and place the middle 2 inches of the section into a clean bucket. Repeat in several other locations and mix soil sample well. Place 2 cups of soil into a plastic bag. If you have more than one sample to submit, remember to label each bag.
To submit any sample for analysis, take it to any of the Cooperative Extension Service office on the Big Island. The Hilo office is located in the Komohana Research and Extension Center and can be reached by calling 981-5199. The office in Waimea is located in the Public Safety Complex next to the Hawaii Department of Health. The phone number is 887-6183. Soil samples are accepted by the Kona Experiment Station staff by appointment. Call Marc Meisner at 322-4896. The Experiment Station is located up the hill from the Cooperative Extension Service Office in Kainaliu, opposite the Aloha Theatre. Payment can be made by cash or check. Credit cards are not accepted at this time.
For more information on this and other gardening topics, visit ctahr.hawaii.edu/Site/Info.aspx or any of the local Cooperative Extension Service offices around the island.
Russell Nagata is the Hawaii County administrator of the University of Hawaii at Manoa College of Tropical Agriculture and Human Resources. He can be reached at russelln@hawaii.edu.