Control Methods and Technical Key Points for the Jujube Inchworm

Also known as the jujube looper or "arched-back worm," it is the "number one enemy" harming jujube trees. Its larvae damage young buds, young leaves, and flower buds, and spin silk that tangles and hinders leaf expansion; in severe cases they can strip all the leaves, while also causing heavy damage to crops such as apple, pear, peach, potato, and chili pepper. The jujube inchworm begins to emerge from the soil in mid-March, and when the jujube buds begin to swell, the larvae start hatching and damaging the jujube buds. Its main biological characteristics are:

1. One generation per year, overwintering as pupae concentrated in the surface soil around the root collar of jujube trees;

2. Adults are sexually dimorphic: the wingless female moth crawls up the tree and mates with the winged male moth, then lays eggs in masses under rough, cracked bark;

3. Older larvae have a large appetite and extremely strong resistance to pesticides;

4. Wingless female moths cannot pass over smooth objects; young larvae can pass over smooth objects but are easily trapped by sticky substances. Based on the growth history of the jujube inchworm, the five lines of defense established by Professor Li Lianchang can be used for control. The specific measures are: first banding, second mounding, third digging, fourth dusting, fifth coating. The first three lines of defense should be completed between March 15 and 20.

Five lines of defense: on the ground within one chi around the base of the trunk, five control measures are used: first banding, second mounding, third digging, fourth dusting, fifth coating. First banding: tightly wrap a strip of plastic film 8-10 cm wide around the base of the trunk at 5-10 cm above the ground, seal the overlap with plastic adhesive or fasten it with small shoe nails, so that female moths cannot climb the tree; second mounding: below the plastic bag, build a conical mound of soil, tamp the surface firmly and make it smooth, and bury the lower edge of the plastic film 1.5 cm into the upper edge of the mound, so that the plastic film is more secure and there is no gap to enter; third digging: dig a small ditch 10 cm wide and 10 cm deep around the mound, with straight and smooth walls, so that female moths that cannot climb up fall concentratedly into the ditch; the above three lines of defense should be completed before Awakening of Insects.

After the adults emerge from the soil, carry out the fourth and fifth lines of defense. Fourth dusting: after the adults emerge from the soil at the Spring Equinox, spread 10% phorate powder or 2.5% trichlorfon powder or 3% parathion or 35% mephosfolan poisoned soil (pesticide-to-soil ratio 1:10) in the small ditch and on the mound to kill female moths in the ditch and on the mound; fifth coating: for the few eggs laid in cracks under clods and stones, they begin to hatch and climb the tree to cause damage around the jujube bud swelling stage; before the larvae climb the tree, apply a ring of larval-killing ointment 1.5 cm above the upper edge of the plastic film (the ointment is made by mixing 10 parts butter, 5 parts machine oil, and 1 part 50% parathion or other contact-killing organophosphorus pesticide) and the efficacy can last 40-50 days.

In jujube-growing areas where the five lines of defense were not applied in time to control the jujube inchworm, pesticides can be sprayed when the jujube trees sprout and unfold leaves and most larvae reach the second instar, to poison the larvae. Commonly used pesticides include: 75% phoxim 1000-fold solution, 50% malathion 1000-fold solution; for older larvae, use 25% deltamethrin 15,000-20,000-fold solution or 20% fenvalerate solution.