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Guy Collins, NC State University Cotton Extension Associate Professor
Keith Edmisten, NC State Extension Cotton Specialist
Dominic Reisig, NC State Extension Entomologist
Charlie Cahoon, NC State Extension Weed Scientist
Phil Wilson, N.C. Department of Agriculture & Consumer Services, Director, Plant Industry Division
Brian Bowers, N.C. Department of Agriculture & Consumer Services, Seed and Fertilizer Administrator
Roger Cross, N.C. Department of Agriculture & Consumer Services, Seed Lab Supervisor
Unfortunately, some of what was predicted in the newsletter article that we released on April 4, 2019, has occurred: (Seed Is Expensive…Protect This Investment!! (Collins & Edmisten)). The points made in that article could still have an impact on the remainder of our planting season, so it’s important to re-read it and consider those points. There have been several reports of poor seed quality and resulting poor stands. This does not appear to be a profoundly widespread issue, and let’s be clear, this does NOT appear to be a variety issue (where poor germ is genetically inherent to a particular variety, or where poor emergence is expected in most situations where that variety is planted), but rather this is merely an isolated issue involving a very few seed lots of certain varieties. Some growers have expressed interest in submitting official samples to be evaluated for warm and cool germination. Below is some information from NCDA&CS regarding the appropriate procedures for submitting seed samples for analysis. Additionally, some growers are facing replanting decisions, which is the primary focus of this article, but these recommendations apply to ALL scenarios where replanting decisions need to be made, regardless of the cause.
Submitting samples for Germination Analysis (Wilson, Bowers, & Cross): North Carolina cotton growers may have experienced some germination issues with cotton seed sold this spring in the state. NCDA&CS Plant Industry Division staff are aware of the issue and are taking samples of the affected lot numbers. NCDA&CS Seed and Fertilizer Field Specialists are collecting official samples for testing currently so as to document the issues. As such, before submitting your own sample, it may be worthwhile to contact Brian Bowers (NCDA&CS) at 919-707-3756 or email@example.com to see if your same lot # has already been tested. Also, if an official regulatory sample analysis is desired, you cannot submit that sample on your own, as an NCDA&CS representative must collect the sample from an unopened seed bag or container.
The NC Seed Laboratory is directly responsible for providing laboratory testing for regulatory and service samples that are submitted by NCDA&CS field staff, producers, seed dealers, university researchers, and consumers. The tests provide assurance to producers, gardeners, and homeowners that seed offered for sale in the state are truthfully labeled as to the variety, germination, and contamination. The following guidelines can be followed if growers desire to send a sample of seed into the NC Seed Lab for testing:
- The careful and deliberate sampling of seed is an important first step in determining the true characteristics of any seed lot.
- The seed sample you take should be fully representative of the entire seed lot. As such, when taking any sample, one should check for any signs of non-uniformity with the seed.
- It is important to fully review the container or package and label information for the lot number, kind, variety, and any seed treatment.
- For sampling small quantities of seed, it is often adequate to include 200-400 seed for testing. This number provides an appropriate amount to provide true statistically-valid results. Should the number of seed be limited, as many seeds as possible should be sent without impacting your garden plans.
- Composite samples may be placed in fully sealed paper bags in a mailing envelope and submitted to the NC Seed Laboratory, NCDA&CS-Plant Industry Division, 1060 Mail Service Center, Raleigh, NC 27699-1060. Overnight deliveries may be submitted to NC Seed Laboratory, 216 West Jones Street, Raleigh, NC 27603.
- Helpful information includes any of the following, if known: Name and address of labeler, kind and variety, brand name, lot number, container weight, and sample date.
- It is critical the name, address and email of the individual furnishing the information be provided.
- Seed Sample submission forms are available at the following links:
- If you wish to report an issue with seed, please contact Brian Bowers, Seed and Fertilizer Administrator, 919-707-3756 or firstname.lastname@example.org or for NC Seed Lab sample questions contact Roger Cross, Seed Lab Supervisor, 919-707-3736 or email@example.com
Note: Presently there are no costs for purity and germination tests conducted for North Carolina Residents
Re-Planting Decisions (Collins & Edmisten): In order to effectively make the best decisions possible, growers should not make replanting decisions until 7 to 10 days after initial planting. In many cases, a full stand cannot be expected in much less a week, even when planting into good conditions. Given the weather we’ve had since April 30th, assuming seed were planted into adequate moisture, the majority of seedlings should emerge after a week has elapsed, and nearly all seedlings (that are likely to emerge) should appear by 10 days after planting. By 14 days after planting, it becomes more unlikely that additional seedlings will emerge, if they were originally planted into adequate moisture. If only 4-5 days have elapsed since planting, don’t rush these decisions, and give it a little more time to emerge before making a decision. Evaluating germination progression before emergence can also give you an indicator as to how many may emerge within the next few days. Growers should make replanting decisions on a case-by-case basis, and potential benefits must be weighed against additional costs (cost of additional seed if applicable, the likelihood of achieving better stands by replanting, time lost, herbicides, thrips management, etc). Research is currently underway to re-visit replanting recommendations in NC. For now, previous research in the Southeast suggests that replanting may generally be justified if approximately half (or more) of the planted area is occupied by 3-foot skips (2-foot skips in more conservative situations, such as late May or June replanting or poor health/status of remaining seedlings that did emerge the first time). When determining how many 3-foot skips are present, remember to give appropriate credit to large skips (for example, a 12-foot skip should be considered as four 3-foot skips). In many cases, spot replanting in certain parts of a field may suffice. We want to make sure that re-planting is likely to be more successful than the initial planting. The next 2 days will bring less than ideal weather in some areas of the state (see the NC Cotton Planting Conditions Calculator for your local planting forecast), but forecasted temperatures appear to be favorable beyond that. Our primary concern now is soil moisture. Many folks received adequate rains over the weekend, but other places received very little. It is important to re-plant into adequate soil moisture, however re-planting shouldn’t be delayed inevitably. Sooner is likely better than later. If we get into late May or June, growers should re-plant using a slightly higher seeding rate (45,000 to 47,000 seed per acre), especially emergence challenges are expected.
Regarding potential impacts on yield, when comparing cotton replanted during the next week or so to cotton planted in late April or very early May, there should be little to no yield impacts due to delayed planting at this point. Replanting before the May 25 insurance cutoff should have little to no impact on yield compared to earlier planted cotton in most years, therefore, with all factors being equal, growers replanting relatively soon could expect similar yields to that of early May planted cotton. Differences between yields of early May and mid/late May-planted cotton strongly depend on weather throughout the summer and if/when fall storms occur, but these differences are not likely due to poor heat unit accumulation or a shorter season for replanted cotton, unless management for earliness isn’t timely, or if replanting occurs beyond the May 25 insurance cutoff date.
Thrips Management (Reisig): If you are replanting cotton, keep in mind that the Thrips Infestation Predictor for Cotton predicts that cotton planted in May will be more at risk from thrips than earlier planted cotton. Although seedlings grow quicker in warmer weather, risk is predicted to increase throughout May as thrips move from wheat and weeds as they dry down to cotton. Because of this, growers should double down on thrips control to avoid delays in crop maturity from thrips damage. First, be sure to use the highest rate of imidacloprid seed treatment available. Secondly, use an in-furrow insecticide or be prepared to use a foliar insecticide once the first true leaf is visible by peeling the cotyledons.
Generally effective in-furrow insecticide options include Ag Logic (3 ½ to 5 lbs) and Admire Pro (9.2 oz). Ag Logic at these rates is very effective when used in combination with a seed treatment. A couple notes about Admire Pro. Since the maximum amount of Admire Pro labeled for soil use in a season is 9.2 oz, if growers have already applied Admire Pro at planting, they cannot use it to replant. Also, since resistance has been documented to the insecticide in Admire Pro (and Velum Total), performance can vary. Still, most growers using both a seed treatment and a full rate of Admire Pro (with good insecticide to seed contact) can expect good control.
A good option for thrips control is a full rate of a seed treatment followed by a timely insecticide spray. We cannot emphasize the importance of timeliness. Even a few day delay can make a huge difference. Sprays target larvae as they emerge from eggs that adults lay in fleshy cotyledons. Therefore, they must be timed when the first true leaf is visible by peeling the cotyledons for maximum efficacy.
Herbicide Considerations (Cahoon): Warrant is commonly applied PRE to cotton in North Carolina. The active ingredient in Warrant, acetochlor, is microencapsulated to improve cotton tolerance. When planting conditions are ideal and cotton rapidly emerges, cotton tolerance to Warrant is excellent. However, when cool, wet conditions persist, Warrant can stunt cotton. Under these conditions, cotton is slow to emerge and therefore exposed to greater concentrations of acetochlor as more of the capsules “holding” the active ingredient break down.
Under replant situations, most of the acetochlor has been released from the capsules as you pull the planter back into the field. Hence, one might expect injury to replanted cotton unless sufficient time elapses for some of the acetochlor to dissipate. So the questions are 1) how long must one wait before replanting to avoid injury, and 2) will tillage be of any benefit? In a no-till situation, data from Georgia suggests waiting at least 3 weeks before replanting cotton into Warrant. If you plan to strip-till before replanting and your ripper shanks run deep enough to bring fresh soil into the planting zone, the replant interval can be shortened to 2 weeks. Research on this very topic is currently underway in NC to generate more local data.
Replanting immediately into Brake, Cotoran, Direx, and Reflex will not be an issue. However, remember you have lost at least some of your residual and your strip-till and/or planter will further disturb residual activity of the herbicide. It would be wise to apply another residual herbicide following replant. My first suggestion would be to use a different residual herbicide following replant than used initially. For example, if you used Warrant + Reflex behind your first planting, apply Direx immediately following replant. Or, if willing to come back early POST, one could apply Dual Magnum/Outlook/Warrant with their POST herbicide of choice after cotton has emerged.