Imidacloprid Insecticide Slows Development of Phony Peach and Plum Leaf Scald

Abstract

<jats:p>Observations in controlled field experiments over 5 years indicated that imidacloprid, applied as a soil drench around the trunks of peach (<jats:italic>Prunus persica</jats:italic>), nectarine (<jats:italic>P. persica</jats:italic> var. <jats:italic>nectarine</jats:italic>) and japanese plum (<jats:italic>P. salicinia</jats:italic>) trees at planting and in the early spring and mid-summer for two subsequent seasons (0.7 g/tree a.i.), slowed the development of symptoms of phony peach disease (PPD) and plum leaf scald (PLS) (<jats:italic>Xylella fastidiosa</jats:italic>) in the trees. After 3.5 years, the percentage of peach trees showing PPD symptoms was 8.5% for the imidacloprid-treated trees compared to 34.3% for untreated trees. After 4.5 years, the percentage of peach trees showing PPD symptoms was 13.1% in the treated trees and 71.4% in the untreated trees. After 3.5 years, nectarine trees in untreated and treated plots showed PPD symptoms in 8.3% and 0.9% of the trees, respectively. After 4.5 years, PPD symptoms in nectarine were found in 32.3% of the untreated trees and 8.5% of the treated trees. Development of PLS disease in plum was also slowed by the trunk drench with imidacloprid in two japanese plum varieties. After 3.5 years, dieback was observed in 55% of the twigs of untreated and 23% of the twigs of treated trees of `Au Rosa' plum and 33% of the twigs of untreated and 12% of the twigs of treated trees of `Santa Rosa' plum.</jats:p>

Diseases Caused by Xylella fastidiosa in Prunus Genus: An Overview of the Research on an Increasingly Widespread Pathogen

“…Between 1929 and 1947, PPD led to the loss of about 1,500,000 peach trees (Turner, 1949). To date, in the United States, PLS and PPD have caused an enormous economic damage, mainly in orchards in Florida and Georgia (Dutcher et al, 2005;Overall and Rebek, 2017).…”

“…On sensitive plum cultivars "Methley" and "Santa Rosa, " many specimens of this insect are found during the summer (Andersen et al, 2008). A study showed that spraying imidacloprid onto the roots reduced the symptoms of PPD and PLS (Dutcher et al, 2005). In fact, imidacloprid is a systemic insecticide against H. vitripennis and many homopteran pests.…”

Phony peach disease: past and present impact on the peach industry in the southeastern U.S.A

“…Imidacloprid, a systemic neonicotinoid insecticide, slows development of epidemics of PD in grapevine plantings (Krewer et al 2002), and was used in peach to determine if a soil drench at planting followed by consecutive applications for five seasons thereafter would reduce incidence or control PPD. Whereas 13.1% of the trees treated with imidacloprid developed symptoms of PPD, 71.4% of the untreated trees developed PPD (Dutcher et al 2005), indicating that annual use of imidacloprid could provide a useful level of control. Resistance to insecticides is a concern when applying chemicals, but there is little cross-resistance with older insecticide classes (Nauen and Denholm 2005;Denholm et al 2002).…”