Dr. Jarrod Hardke
June 10, 2016 No. 2016-13 www.uaex.edu/rice
This rice growing season has been all about time and patience, waiting for the crop to make a serious move. The patience finally paid off in the form of warm temperatures and bright, sunny days. The crop seems to be kicking into gear, and not a moment too soon.
Table 1 shows current crop progress in the state as far as acreage reaching ½” internode elongation. Beginning internode elongation (BIE, green ring) occurs 5-7 days prior so that’s where the majority of the crop should be right about now.
Table 1. Percent of Acres Reaching ½” Internode Elongation by Week According to DD50 Enrollment.
Midseason Nitrogen Reminder
Remember the midseason N discussion from last week. While we’re at the traditional timing for midseason N applications (internode elongation), the new recommendation is to wait at least 3 weeks since the preflood N was incorporated AND be past green ring (BIE).
With the cool conditions some of the crop went through I would prefer to push that gap to 4 weeks to make sure we’re done taking up the preflood N. If you’re worried about missing ½” with the midseason shot, don’t be – you will still the response or an even better one by waiting.
All of our data shows that if you make the midseason application too early there is a good chance that you will receive NO benefit from it. Wave goodbye as that urea hits the water if you apply it earlier than 21 days since the preflood N was incorporated.
Yes – this includes those fields that have only been flooded for a week or two and are already at elongation. You still need to wait at least 3 weeks, preferably longer.
If you have reason to believe that your preflood N was insufficient – wrong rate applied, wet ground, flooding delayed – and the crop shows deficiency then consider making a move. But if you applied preflood N properly on dry soil and flooded timely, you wait before putting out midseason N.
Fig. 1. Rice crop progressing rapidly in favorable conditions.
Zinc and Shuffling the Flood
Zinc deficiencies continue to be reported as more rice has been flooded for a couple weeks (Fig. 2). If you have bronzing of the lower leaves and a bright yellow midrib that’s a great indicator of a zinc problem.
The recommended correction for this problem is to immediately drain the flood. There’s rarely a situation that allows you to avoid draining, you just have to do it. Once new leaf and root growth occurs apply 1 lb Zn/acre. A few days later apply 100 lbs of ammonium sulfate and reflood.
Yes, you absolutely need 1 lb Zn/acre of a chelated Zinc. If the product contains 10% Zn that means you need 1 gal/acre of that product. Don’t let anyone talk you into a reduced rate or a different type of product.
If you have any doubts about the Zn deficiency (sometimes its less obvious) or feel something else may also be in play – send plants off for tissue analysis. Proper diagnostic analysis involves sending in a sample that looks deficient as well as a sample from a good area of the field. This allows for comparison of values within the field as opposed to comparing strictly to textbook values that may not be as representative of your crop in its current stage and situation.
Fig. 2. Zinc deficiency in rice.
Chinch Bugs Rare But Problematic
A great example of how damaging a chinch bug infestation can be is shown is Fig. 3-4. Ryegrass burned down at planting seemed to be a home to them and once the ryegrass fully died they moved onto the rice. Note the large area where the rice is gone surrounded the dead ryegrass. At enough of a density, clearly chinch bugs can kill seedling rice. But remember they like to hide in cracks in the soil and are often missed when scouting as a result.
Fig. 3. Stand loss due to chinch bugs.
Fig. 4. Chinch bugs on young rice.
The DD50 program can be found at http://DD50.uaex.edu. Enroll fields now to help with timing most major rice management practices.
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We sincerely appreciate the support for this publication provided by the rice farmers of Arkansas and administered by the Arkansas Rice Research and Promotion Board.
The authors greatly appreciate the feedback and contributions of all growers, county agents, consultants, and rice industry stakeholders.