Hello,

I hope you are doing well. 

When it comes to N (since this is very mobile), I would put a starter and come later with the remaining rate. You could also take PSNT samples (pre sidedress Nitrate test) to fine-tune your application rate. 

Are you rotating your sweet corn with vegetables? If not, have you thought about using atrazine + glyphosate since the ladder has no residual activity. Also, make sure you pay attention to the PHI (pre-harvest interval) and do not wait until the weeds are too tall. The earlier you control the escapes the better.

Please feel free to give me a call if you have any questions.

Ricardo Costa

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Ricardo,

Thank you for your response, but I don't think you answered my question completely and you raised some new questions for me.

1. Can I use 2, 4 D and spray it over sweet corn to control broad leaf weeds?  When (after the corn emerges)?  Should I use it, or should I just cultivate inbetween the rows (how many times since compaction can be a problem?) and hope for the best?

2. You say I should use starter fertilizer for the sweet corn.  What is that?  Can I buy this in solid form and broadcast?

3. As I said I have soil tests done, but now you are recommending PSNT samples.  Who does that test, how much does that cost, and how do I adjust bag fertilizer at preset concentrations of NPK to meet the need?

4.  I am rotating with other vegetables and I don't think atrazine is an option. 

5.  One, last question: Corn seed germinates at 50 degrees F.  Does that mean air temperature (high or low for the day), or ground temperature (average for the day or high temperature for the day)?

Tried to call you a couple of times. 

Question # 0011854

Terry

Hello Terry,

I hope you are doing well. Sorry for not picking up your call. Feel free to call me again and leave a voicemail so I can call you back.

Below are my answers.

1. Yes, you can apply 2-4 D as a post. Just check the label first to see what are the recommendations. For example, check this label (page 3)  http://www.cdms.net/ldat/ldEL8000.pdf for recommendations if using 2-4 D amine ( a generic brand). You need to take extra preoccupations if spraying when corn is over 8 inches. 

I try to avoid cultivation as much as I can, but if you don't have access to an herbicide that becomes your main option (especially in organic settings). Weed development and growth will be your indicator of how much cultivation needs to be done. Usually, in the beginning, you need to carry on cultivation more often (sometimes even 2x week). Your goal is to cultivate when the weeds are very small. You will be able to cultivate until right before canopy closure. 

2. Starter fertilizer is defined as small amounts of plant nutrients – nitrogen (N), phosphorus (P), and potassium (K) – placed in close proximity to the seed, usually at planting. Placement can be directly below, to the side, or to the side and below the seed. Growers sometimes consider broadcast or liquid fertilizer application to the soil surface as a "starter"; however, these should not be included because nutrient placement is positionally unavailable to early seedling growth. To be a "starter," nutrients must be strategically positioned to enhance early seedling vigor and development. The amount you will apply will depend on your soil tests and how much you want to apply at planting (a smaller portion) and then later on (the remaining amount). 

3. PSNT stands for Pre-sidedress Nitrate Test and is valid only for Nitrogen. That is only if you want to fine-tune your Nitrogen application. We have put a short article covering PSNT https://www.canr.msu.edu/news/identifying_fields_and_preparation_work_for_pre_sidedress_soil_nitrate_test . Again, this is not mandatory, it was just an idea to fine-tune your Nitrogen application. You could try that next year if you don't have the time or resources to do this season. 

4. Well, not necessary.  A general rule is: Maximum of 1 lb ai atrazine before July 1, if the soil has at least 3% Organic Matter or 20% clay. Less OM, use less atrazine or use it pre only. Again, make sure to check the label before applying it. 

5. The minimum (not the mean) threshold temperature for corn seed germination is 50 degrees F in the seed zone. Corn will germinate and emerge slowly and unevenly when soil temperatures are less than 50 degrees F.

Please let me know if you have further questions,

Have a great weekend,

Ricardo Costa