Control methods for the blackberry pest, the sloe bug (Dolycoris baccarum)

Blackberry is one of the third-generation fruits recommended to the world by the Food and Agriculture Organization (FAO) in 1993. In 1995, the Xingnong Seed Company of Xuecheng District, Zaozhuang City, Shandong Province, successfully introduced it from the United States, and in 1997 it was listed by the Municipal Science and Technology Commission and the Municipal Finance Bureau as a key agricultural extension project. Because of its good nutrition, unique flavor, suitability for fresh eating and for processing into juice, canned goods and the like, the fruit is in short supply. Blackberry has few pests and diseases, and their occurrence is also mild; field cultivation generally requires no pesticides, so it has become a “green food” much welcomed by people. In recent years, in the blackberry production orchard of Nanshi Town, Xuecheng District, it was found that the sloe bug (Dolycoris baccarum) is damaging blackberry to varying degrees. The occurrence, damage situation and control techniques of the sloe bug in blackberry orchards are briefly described as follows:

Occurrence and damage situation: The sloe bug has 3 generations a year, overwintering as adults in dead branches and fallen leaves, soil crevices at the roots, crevices of buildings relatively close to the blackberry orchard, crevices of tree bark and other sheltered, sun-facing places. After overwintering, it begins to migrate into the blackberry orchard successively in mid-May and completes 2 generations on blackberry. May to July is the peak period of damage. Adults and nymphs like to perch among the fruit clusters and pierce and suck the fruit juice; sometimes several adults and nymphs compete for food on a single fruit. In April and May, the sloe bug damages the young buds of the plants, causing young leaves to die and new shoots to suffer “broken-head madness”. When young green fruits are damaged, the fruit grains cannot develop and swell normally, becoming deformed fruits. When ripe fruits have their sap pierced and sucked, in sunny and dry weather the fruit grains shrivel and lose their luster; when rain is encountered, the fruit grains fade and deteriorate, becoming whitened fruits with poorer taste and losing their commercial value. It generally causes a 5% reduction in yield, and in severe cases about 15%.

Control techniques: To control the sloe bug damaging young shoots, buds and leaves in April and May, spray with 40% omethoate 1500-2000 times dilution.

In the early stage before the fruit ripens (June to July), when adult and nymph sloe bugs perch among the fruit clusters and cause damage, and when the density reaches the control threshold of 2 insects per cluster, high-efficiency, low-toxicity and low-residue pesticides should be selected for control, generally spraying the pesticide solution evenly onto the fruit clusters. If using 80% dichlorvos 2000-3000 times dilution for control, note that it should be applied more than 3 days before harvest; if using 90% crystalline trichlorfon 800-1200 times dilution for control, it should be applied more than 7 days before harvest; if using 20% fenvalerate emulsifiable concentrate 3000-5000 times dilution or 20% fenpropathrin 3000-4000 times dilution for control, it should be timed 15-20 days before harvest, so as to ensure the safety of the fruit at harvest, and the control effect generally reaches more than 85%.