Above are two photographs. The first one appeared in an earlier edition of Field Notes showing Command injury to Cheniere. The second one was taken Thursday in the same field. While there is a little stand loss most of the rice has recovered very well. If the entire field had been affected the same way some yield loss could have been expected, but not in this instance.
Late one afternoon this week I got a call to look at some “rice that looks like it is dying.” From a distance there were apparent rust colored areas of the field that corresponded to areas of the field that had remained dry longer than they should have. Close-up views exhibit one of the worst cases of blast I have seen since 1995 when it ripped through many Bengal fields. The variety here is CL261. We know it is susceptible to blast and have documented it in this variety since its release, but this is the worst case I have seen. The plants have about 3 crown nodes so it is much too early to apply any fungicide. Two more factors complicate the issue: first, it is a seed rice field; second it is in a field where soybean samples were shown to have aerial blight that is resistant to Quadris. In this case the preferred fungicide would be Gem applied at heading to control blast. Because Gem and Quadris are so closely related chemically something else will have to be applied to control sheath blight. A section 18 for a new fungicide has been applied for, but not granted yet. A few seasons ago a similar outbreak occurred in another variety because the field had dried out. This always aggrevates blast problems. A good deep flood is one of the best managerial things that can be done to at least lessen blast disease. It will not prevent it or control it, but it sure makes a difference in the severity of the disease.
Below is a picture of yellow nutsedge exhibiting two characteristics that contribute to its ability to be a serious pest. The “nut” part of its common name is derived from the structure shown at lower left. It is not a nut, but is actually a tuber, an enlarged part of the rhizome. The white, root-like structures are also rhizomes which are underground stems. If the stems were above ground they would be called stolons. These structures are underground and well protected from herbicide sprays. To really get to them requires a good translocated herbicide. If you plow and cut the tuber off from the main plant it just produces a new plant from the tuber. The plant can also produce lots of viable seed enabling it to survive by more than one method. One way to distinguish yellow nutsedge from purple nutsedge is to cut the tuber and smell it. If it has a petroleum odor it is purple nutsedge. Purple nutsedge also has a more blunt leaf tip than yellow nutsedge. The tubers of purple nutsedge are hairy compared to the fairly smooth yellow nutsedge tubers. Yellow nutsedge is actually sold as Chufa to be used in wildlife food plots. Apparently turkey will scratch up the tubers and eat them. One biologist said he found the crop of Teal killed in a rice field full of the tubers. If they would leave the rice seeds alone and selectively consume the tubers it sure would help.
Below are three photographs taken in the same field where Command had been applied with a ground rig. The applicator made one pass on each end to provide a turn around area. Then he started making linear passes from the east side of the field working his way to the west. In the top photograph the clearly damaged area on the right is the first pass. The green area is the east half of the field. The bare area across the top of the picture is the west side of the field. We could not determine if there was some extremely odd mixing problem that caused a light to normal dose to be applied at the beginning then a heavy rate later as more product mixed or if there was some sort of mechanical malfuntion in the spray rig. It does have electronic spray controllers so I suppose it is possible that caused the strange injury pattern. The severly damaged area will have to be replanted. This is the most severe Command injury I have ever seen.
Last week we were called to a hybrid rice field where there were issues with stand loss. We could not determine any specific cause, but did note the presence of thrips on nearly every plant. While the number was fairly large there presence was not especially alarming to me because I have always seen them on seedling rice. The field was treated with Dermacor which is not expected to control thrips. We also suspected some seedling disease. In the past we planted at high enough seeding rates to compensate for seedling loss, but the low seeding rates of hybrids magnifies any stand loss. Without a definitive cause we could only make a couple of suggestions; apply an insecticide or add some starter nitrogen. I followed up with the farmer who said he chose to add starter fertilizer and while the stand is still thin the seedlings are growing better. Nearby crawfish ponds may have had some influence on the decision.