Back to Dr. N. V. Hue

Like an unwelcome houseguest, some problems seem to stay. University of Hawaii studies show that coffee (Coffea arabica), an important agricultural crop in Hawaii, is yielding well below its potential because of poor soil nutrition and soil-borne roundworms call plant-parasitic nematodes. 

In 2000, Hawaii growers produced about 9.5 million lbs of coffee (parchment basis) that generated nearly $ 24.5 million for the states coffee farmers. The sad part of this story is that farmers are being robbed of another $20-25 million.

Results of a state-wide survey in 2000 showed that plant-parasitic nematodes increased dramatically during the past 10 years. The University of Hawaii researchers found five major groups of nematodes associated with coffee. Three of these groups are very damaging to coffee and can actually kill trees. The kinds of nematodes and the locations where they were found are illustrated in Figure 1. The percentage figure shows the frequency that the different groups of nematodes were found. This information provides an estimate of their occurrence in coffee orchards. 

Improper plant nutrition also will cause yield loss. This can happen because of excesses causing toxicity or through deficiencies by which the plant does not have the nutrition needed to grow properly. Such unhealthy coffee trees cannot produce enough cherries to be economical. Manganese was high enough in several areas as shown in Figure 2 to cause toxic damage to the coffee trees. Zinc and calcium were nutrients that were commonly too low to expect the plant to grow and yield well.

Fig. 1. Nematode distribution in Hawaii.

Fig. 2. Most limiting soil nutrients for coffee growth in Hawaii.

The solution to the nematode and nutrient problems begins with the education of growers that they have a problem. The University of Hawaii researchers have teamed up with Cooperative Extension and some of the leading producers and processors to have workshops. These sessions demonstrated how to recognize the unwelcome guests. Some of the growers are now working hard to make other growers aware of the nutrient and nematode problem. 

The information generated by the researchers is helping them set priorities in finding practical solutions. The grower organizations are shifting their funding support to assist the researchers in solving the nematode and nutrition problems. 
Growers must test the soil and plant tissue for nutrients concentration. Only with the prescription provided by testing can the grower optimize their fertilizer program. Where nematodes are causing yield loss, the coffee farmer can improve their production by grafting onto resistant rootstocks.

Back to Dr. N. V. Hue