ISHS Acta Horticulturae 810: IX International Vaccinium Symposium
ORGANIC PRODUCTION OF WILD BLUEBERRIES I. INSECTS AND DISEASES |
| Authors: | F. Drummond, S. Annis, J.M. Smagula, D.E. Yarborough |
| Keywords: | Vaccinium angustifolium, sulfur, lowbush blueberry, organic fertilizer, pruning, insects, disease, Monilinia vaccinii-corymbosi, mummy berry |
| Abstract:
Little is known about the responses of wild lowbush blueberry diseases, insect pests and their natural enemies to production practices in Maine, especially those common to organic production. In 2004 to 2007 a replicated field experiment was conducted to assess the main and interactive effects of pruning (mowing versus burning), sulfur application (0 or 1120 kg/ha), and fertilization (0, 22 or 45 kg N/ha) on a crop managed for two, 2-year production cycles in Amherst, Maine, USA. Plant growth response, yield, fruit quality, weed, disease, and insect populations were assessed. Effects on diseases and insects are reported in this paper. In 2005 and 2007, treatment plots pruned by burning had a greater number of red-striped fireworm (Aroga trialbamaculella Cham.), grasshoppers (Melanopus spp.) and blueberry thrips (Frankliniella vaccinii Morgan & Catinathrips kainos O’Neil) than mowed plots, possibly because of the significantly greater number of natural enemies (ants and spiders) that were found in mowed plots. Sulfur treatments interacted with pruning treatments for populations of red-striped fireworm in 2005, and thrips and tarnished plant bug in 2007. Higher grasshopper densities were associated with higher fertilizer rates. Host plant quality, expressed by leaf micronutrient levels, affected insect pest community structure, suggesting that differential responses to organic management practices might play a role in determining organic pest complexes. Fifteen percent of the variation in the reduction in yield was associated with blueberry thrips and grasshopper populations over the two crop cycles. There was no significant effect of the type of pruning or for sulfur treatment on the incidence of Monilinia blight disease (caused by Monilinia vaccinii-corymbosi (Reade) Honey) in either 2005 or 2007. The low level of disease, <6% in 2005 and <1% in 2007, indicates that there were initially low levels of Monilinia inoculum in the field. | |
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