A Detailed Explanation of the Occurrence Patterns and Control Methods of the Jujube Leafroller

The jujube leafroller, also known as the jujube sickle-winged tortrix moth, commonly called the leaf-sticking worm, is one of the important pests of jujube trees. The larvae spin silk to roll leaves for feeding, rolling leaves longitudinally into a dumpling shape, or using silk to bind several leaves together. The larvae also bore into and feed on fruit attached to leaves, greatly affecting yield.

1. Occurrence patterns This pest has 3 generations per year, overwintering as pupae in rough bark crevices on branches and trunks. Adults hide by day and emerge at night, are strongly phototactic, and lay eggs 1 to 2 days after emergence; eggs are mostly scattered on smooth small branches and jujube spurs. The egg stage lasts 10 to 25 days, and the peak period of first-generation larvae occurs in early May. At this time jujube trees are at the budbreak and leaf-expansion stage; the larvae first gnaw on jujube buds and tender leaves, and after leaf expansion they spin silk to stick several leaves together and hide inside to feed on the leaves. Each larva can damage 6 to 8 jujube leaves, and heavy leaf-sticking occurs in late May. After the larvae mature, they spin cocoons and pupate within the rolled leaves, and first-generation adults appear from early June to early July. After this generation, eggs are mostly laid on both sides of the midrib on the leaf surface, with an egg stage of 3 to 12 days. Second-generation larvae occur from mid-June to late July, right around the flowering period, damaging leaves, flowers and young fruit. Third-generation larvae occur from late July to mid-October during the fruit coloring period, damaging leaves and fruit, with the most severe damage from late August to early September. After early September, the larvae successively mature and bore into areas such as under the bark and inside tree holes to pupate and overwinter.

2. Control methods 1. Before mature larvae pupate in early September, tie grass bundles on branches and trunks to attract larvae to pupate and overwinter. In winter or early spring of the following year, remove the pest-attracting grass bundles together with bark scraping and dispose of them in a centralized way; the effect is relatively good.

2. The peak hatching period of each generation of larvae is the key period for chemical control, and particular emphasis should be placed on controlling the first-generation larval stage. This is because this generation occurs uniformly and chemical control gives better results. When the young jujube shoots grow to about 3 cm (that is, the peak hatching period of first-generation larvae), spraying 50% fenitrothion emulsifiable concentrate at 1000 to 2000 times dilution, 50% naled emulsifiable concentrate at 500 to 600 times dilution, 2.5% deltamethrin emulsifiable concentrate at 4000 times dilution, 20% fenvalerate at 3000 times dilution, or 80% dichlorvos at 1500 times dilution all give good results. If the outbreak is severe, a second spray can be applied before and after jujube trees show flower buds; at this time it is already the second-generation larvae damaging flower buds, flowers and young fruit, and if spraying is not timely it will cause dead flowers and fruit drop, seriously affecting yield. In addition, spraying 50% parathion at 2000 times dilution during the adult emergence period in early spring has a killing effect on both adults and eggs.

3. Adults are phototactic, so black light traps can be set up to trap and kill adults.