Weed Flora and Management Practices in Peach Orchard Fields in Korea

Abstract

In Korea, fruit represents one of the main categories of economic crops. The country’s fruit tree planted area was 155,000 ha in 2005, which is seven times larger than the acreage of orchards in 1955 (Ha and Chung, 2012). In particular, the area planted with peach trees has increased by around 3%, from 13,908 ha in 2011 to 14,210 ha in 2012. The yield of peaches ranked forefront in all fruits (Hong et al., 2012). In the face of the progressive increase in peach tree area, a series of problems have emerged in peach orchards, such as labor shortages, lagging product sales, and insufficient use of science-based management technologies. For these reasons, weed management methods are especially worthy of further study through surveys of weed flora. Weed flora is a common component of orchard ecosystems. On the one hand, an abundance of weed species can increase population diversity in orchards. A previous survey of weeds was carried out in the Chungnam region; its results showed that 75 weed species belonging to 26 families were identified in orchard fields and that Echinochloa crus-galli was the most dominant of the weed species with high densities (Choi et al., 2009a). Additionally, Park et al. (2005) reported that weed ranking in orchards according to dominance had changed compared to that reported a decade ago. On the other hand, weeds bring about some serious adverse effects for peach trees. These negative impacts are mainly divided into environmental and biotic effects. Environmental effects can mean competition for light, water, and nutrients between weeds and peach trees (MacRae et al., 2007). Peach tree yields, rootstock, and leaves are affected by weed competition (Tworkoski and Glenn, 2001). In contrast, the term ‘biotic effects’ can imply that weed species are known favorable hosts ABSTRACT. This study was carried out two surveys in 2015 to monitor weed occurrence and determine the most troublesome weeds in peach orchards of Korea. The first survey identified 56 taxa belonging to 23 families including 27 annuals, 11 biennials, and 18 perennials. Based on importance values, Conyza canadensis (5.12%), Plantago asiatica (4.17%), and Trifolium repens (3.86%) were the dominant weeds in the first survey (from April to June). Seventeen exotic weeds were identified in the first survey, including Conyza canadensis, Trifolium repens, and Chenopodium ficifolium. The second survey (from September to October) identified 42 weeds belonging to 19 families including 23 annuals, 5 biennials, and 14 perennials. According to importance values, Digitaria ciliaris (8.00%) was the most dominant weed, followed by Echinochloa utilis (6.61%) and Rorippa palustris (6.48%). There were 12 exotic weeds, including Taraxacum officinale, Rumex crispus, and Trifolium repens. Additionally, according to Braun-Blanquet’s scale showed that the dominance value was level 1 (41.98% and 46.43%, respectively) in two surveys. Currently, 40% of the total surveyed peach orchards applied herbicides for weed control. These results could provide basic data to assist orchardists in selecting the most suitable weed management methods; thereby, reducing labor inputs and effectively lowering costs while improving fruit yields in peach orchards of Korea.