Damage Symptoms of Rice and Rose Thrips and Methods of Control with Pesticides

Thrips is the collective term for insects of the order Thysanoptera in the class Insecta. Larvae are white, yellow, or orange, while adults are yellow, brown, or black; they feed on plant sap or fungi. Rice and rose thrips are the most common, so what are their damage symptoms? How do you control them? What pesticide should you use? Let's take a look below.

What are the damage symptoms of rice and rose thrips?

I. Rice

Rice thrips belongs to the order Thysanoptera and has rasping-sucking mouthparts. When causing damage, it uses its mouthparts to puncture young, tender parts of the rice plant such as leaves and glumes, and sucks the sap that flows out of the rice plant. On damaged leaves, small yellow-white spots or micropores appear, after which the leaf tips gradually roll lengthwise and turn withered and yellow; in severe cases, whole patches of seedlings can turn yellow and red, as if scorched by fire. When rice seedlings are severely damaged, the greening-up of the rice plants is affected and tillering growth is hindered, and the seedlings become stunted. When damaged at the booting stage, the development of spikelets is affected, and only white filamentous glumes are produced. When damage occurs at the flowering stage, the thrips enter the glumes to damage the ovary, destroying the floral organs and forming shriveled grains or empty husks.

II. Rose

Old leaves lose their green color, new leaves curl, and tender tips and flower buds wither; when pinched by hand they feel as if they have been scorched dry, with a crisp, crumbly feel. The stems have spots and speckles, and may even become deformed. Petals lose water and appear unclean. Leaves damaged by thrips become smaller, harder, and more brittle.

How do you control rice and rose thrips?

I. Rice

1. Weed control to prevent insects. Clear weeds and dead branches and fallen leaves from the edges and borders of fields to reduce overwintering sites and important food sources for rice thrips. This is an effective measure for addressing the initial sources of rice thrips infestation; when using pesticides to control rice thrips, weeds near the rice fields should also be sprayed.

2. Rational layout of rice varieties. Rice thrips occurs over a long period; therefore, if the layout of rice varieties is unreasonable, and rice of different variety types and different maturity periods is planted in an intermingled way, rice thrips can migrate among the rice fields and cause damage. Therefore, rice fields of the same type and same variety should be planted together in a concentrated manner.

3. Protect natural enemies. In addition to pests, rice fields contain many natural enemies that can prey on thrips, such as spiders, true bugs, and ladybugs, which have a certain suppressive effect on thrips populations. When spraying pesticides to control rice pests, pesticides should be applied rationally to protect natural enemies, so as to give full play to the natural enemies' control of pests.

II. Rose

1. Based on the characteristic that thrips hide by day and come out at night, it is recommended to apply the pesticide in the afternoon.

2. Thrips has strong concealment, so the pesticide needs to be systemic or have an organosilicon adjuvant added, and pesticides with a long duration of efficacy should be chosen as much as possible.

3. If conditions permit, it is recommended to combine fumigation of the greenhouse with foliar spraying.

4. Prevent in advance; do not wait until the infestation is rampant before applying pesticides.

What pesticides are used for rice and rose thrips?

I. Rice

Generally, when the rate of rolled leaves in seedling fields reaches 5% and the number of insects per 100 plants reaches 100 to 200; or when the rate of rolled leaves in main fields reaches 10% and the number of insects per 100 plants reaches 200 to 300, this is the appropriate period for pesticide application, and the pesticide should be applied as soon as possible. For the pesticide, you can choose 10% nitenpyram aqueous solution, 1% emamectin benzoate emulsifiable concentrate, 10% imidacloprid wettable powder, 20% acetamiprid soluble powder, etc. In addition, after rice is damaged, its growth becomes weak; depending on the actual situation, appropriate supplementary fertilization can be carried out.

II. Rose

For example, Pichongxiu, fenvalerate, Actara, etc., or choose a symptomatic insecticide according to the symptoms. In addition, the best time to spray is in the evening when the light is dimmer, at least twice a week.