Simple Diagnosis and Control Methods for Rice Deadheart

I. Simple Diagnosis of Rice "Deadheart"

1. "Deadheart" caused by insect pests. Sesamia inferens, Chilo suppressalis, Scirpophaga incertulas, mole crickets and other pests damaging rice can all cause "deadheart," and the main differences are: (1) Sesamia inferens: the insect holes are large and there is much frass, and the frass is generally deposited between the rice leaf sheath and the stem. The leaf sheaths and leaves of the damaged rice all turn yellow. The damage is more severe at the edges of the rice field and lighter in the middle of the field. (2) Chilo suppressalis: after the eggs hatch, the young borers first gather inside the rice leaf sheath to feed and cause damage; on the outside of the damaged leaf sheath, water-soaked yellow spots first appear, then it gradually turns yellow and dies. After the young borers grow slightly larger, they bore into the rice stem, causing the tip of the rice flag leaf to turn yellow, and in severe cases the central leaf dies. The bored rice stem has insect holes, with little frass outside the holes and more frass inside the holes. (3) Scirpophaga incertulas: the young borers first gnaw on the rice central leaf, causing the central leaf to lose water and roll longitudinally like a scallion tube, appearing greenish-white, commonly known as "false deadheart." Pull out the curled central leaf, and a neat cross-section can be seen. If the borers continue to cause damage, bite through the central leaf and destroy the growing point, then the central leaf completely dies, becoming "true deadheart." The bored rice stem has relatively small insect holes, with no frass outside the holes and white fine granular frass inside the holes. (4) Mole crickets: they bite off part or all of the rice clump from the base, causing the rice central leaf to turn yellow and die. The damaged rice is easy to pull up as a whole plant, and there are no insect holes or frass on the rice stem. This kind of deadheart generally occurs only when the rice field is being dried or because of long-term drought and no water in the rice field.

2. "Deadheart" caused by diseases. Rice virus diseases and bacterial leaf blight can both cause rice "deadheart," and the differences between the two are: (1) Virus diseases: the deadheart symptoms are similar to the deadheart caused by Scirpophaga incertulas, but there are no insect holes or frass on the rice stem, the central leaf is not easy to pull out, and when the leaf is pressed between glass slides there is no bacterial ooze. (2) Bacterial leaf blight: it occurs mostly at the rice tillering stage. After onset, the central leaf or the 1-2 leaves below the central leaf of the diseased plant first lose water, curl, become green-wilted and necrotic, and afterward the other leaves also gradually curl, become green-wilted, and finally all the leaves of the whole plant die. Take a small piece of fresh diseased leaf, press it between glass slides, and examine it against the light; yellow bacterial ooze can be seen flowing out at the openings of the leaf veins.

II. Control Measures for Rice "Deadheart"

1. For deadheart caused by borer damage, targeted insecticides such as "Regent," "Teshaming," and "Chongcuo" can be sprayed for control.

2. For deadheart caused by mole cricket damage, when the rice field is being dried, poisoned bait such as wheat bran mixed with "trichlorfon" can be used to trap and kill them.

3. For deadheart caused by virus diseases, before sowing rice the rice seed should be soaked with "strong chlorine essence," and good control work should be done against virus-carrying insects such as rice planthoppers and leafhoppers.

4. For deadheart caused by bacterial leaf blight, in addition to doing a good job of disinfecting rice seed, at the early stage of bacterial leaf blight onset, targeted agents such as "Shibaoling" and "Yekuning" should be sprayed in time for control.