Abstract

From the winter of 1969–70 to the summer of 1973, severe yield and quality reductions occurred on field grown tomatoes (Lycopersicum esculentum Mill) in the Kona district on the Island of Hawaii. Symptoms of this mysterious disease included blossom drop, poor fruit set, hollow, small, and almost seedless fruits, and a less luxuriant appearance. A definite atmospheric haze appeared at this time, and was apparently caused by fumes from active and degassing vents located 75 km away and associated with Kilauea Volcano since the volcanic eruption period coincided with the appearance of the haze. Tomato plants under plastic rainshelters grew normally. Since rainwater was suspected of causing the symptoms, it was analyzed and found to be acidic (pH 4.0) and to contain appreciable quantities of Cl⁻ and SO₄^2- plus 27 detectable organic compounds in the ppb range. When tomato leaf discs were immersed in rainwater samples, more Ca, Mg, and K were leached from these acidic samples than from less acidic rainwater samples and the distilled water controls. In a pollen germination medium containing rainwater, pollen germination and tube lengths decreased as the pH of the rainwater decreased. However, since increasing the pH of the acidic Kona rainwater with NaOH did not increase pollen germination, factors other than pH are suspected to cause poor pollen germination. The pH of rainwater samples from a single heavy rainfall were less acidic than from cumulative samples of lighter rainfalls.

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