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Deer Park, WI

Last Saturday I introduced scientific logic in support of post-set vegetative growth, focusing on the importance of leaves, vine tips, and roots late in the season. I wanted to capture the thoughts in a post to generate some pre-season buzz.

Foremost, a principle that must be accepted: post-set vegetative growth feeds the pumpkin. Please dont argue this. If you do, be prepared to explain how the leaves/branches at the top of an apple tree have no impact on the developing apples below. This capacity is due to the presence of PHLOEM, the channel system in plants that connects the leaves (source) to the roots, fruits, and shoots (sink).

Understanding the (seemingly) reverse flow of phloem helps us understand the value of late season growth tips. Plants, like people, produce growth hormones. These growth hormones are produced in large quantities in the vine tips, most notably the main vine tip. The hormones signal the rest of the plant to tell everyone that its still growing. Hormones, produced in vine tips, flow through phloem all the way into the tips of the roots. Some hormones tell the roots to keep on growing and pulling water, cuz there's plenty of growth action still runnin up on top.

3/16/2011 8:54:06 PM

Deer Park, WI

Not only do the vine tips continue signaling growth late season, the vine growth provides a pressure relief outlet for potential foamers. Dual benefit buffer system here.

But wait, there's more. Leaves make sugar. Sugar is energy. Energy is needed to support pumpkin growth. Tired, worn out, battered leaves dont make sugar. Ensuring late season growth requires healthy late season leaves. Im advocating for managed late season leaf growth to continue fueling photosynthesis.

Lastly, encouraging secondary roots in post-set growth will only serve to fuel the pipeline of water and nutrients. Re-read the second paragraph to understand why.

I'll end with this potent reminder: Sources deliver nutrients to the closest sinks. The closer a source is to the pumpkin, the better. This means nurturing post-set growth around the pumpkin. See my diary post for a proposed plant layout that maximizes the above conditions.

www.bigpumpkins.com/Diary/DiaryViewOne.asp?eid=152032

3/16/2011 8:54:16 PM

Deer Park, WI

The astute observe will that I have diverted the main vine to the left where it meets the pumpkin stem. Of particular note, I have the secondary vine at the pumpkin node diverted to the right.

*shriek*

Leaving the secondary attached to the vine/stem node has been a classic no-no. the potential for vine stress here is significant. However, if one can manage this scenario appropriately, I believe the potential benefits will be worth it.

By season's end, you'd have two primary pipelines drawing nutrients past the pumpkin, assuming you've left vine tips growing to signal back to the crown root system.

now, when you consider that sink strength is a function of sink mass (read: pumpkin weight), the pumpkin will be literally stealing the nutrients that the vine tips are signaling for. And since the vine tips will not be getting all they ask for, because of that thieving pumpkin, they signal harder for more water and nutrients.

Conceivably, this will continue to drive growth late season.

3/16/2011 9:05:09 PM

[email protected]

Interesting idea Joe. In your example in your diary I see you still have the vast majority of growth, roughly 70%, "behind" the fruit. I like the concept, I may have to give it a try on a couple plants this year.

What if the plant were pruned so that only a couple secondaries were left to grow past the fruit and the rest was filled in with tertiaries? This could increase the number of growth tips past the fruit.

3/16/2011 10:41:55 PM

Massillon, Ohio

Do secondary vines have more power in them (so to speak) than tertiaries? If so, why not loop the main back around to its original path direction, so you could grow secondaries from both sides of the main the rest of the way down....rather than your diagram, showing the last secondary to the right, growing tertiaries down.
Love this post. Anxious to hear more!!

3/17/2011 10:08:31 AM

Deer Park, WI

My drawing is not entirely to scale; I wasnt try to convey a percentage of foliage pre/post set. However, I was attempting to convey a point by plopping the pumpkin in the center of the diagram. Again, distance between sinks and sources is significant. Generally speaking, having the pumpkin in the center of the plant shortens the relative distances to the various sources on the plant.

Regarding the "power" of vine tips. The main vine tip is referred to as the "apical meristem", a fancy word for the major growing point in the plant. The apical meristem does contain the highest concentration of hormones. Im unsure if secondary meristems are more potent than tertiary tips. Your point is a good one...if secondary tips are more potent, then returning to a more x-mas tree style pattern post-set would take advantage of this. I chose to route the main the way I did in order to maximize main vine length, respecting that the apical meristem will be a primary source of hormone signaling. Secondly, in my experience, the tertiaries on the right hand side of the diagram would fill in much faster than secondaries if the main was allowed to grow x-mas tree style. One could go either way on this matter, depending on preferences.

3/17/2011 11:12:13 AM

Minnesota

Nana, i like your thoughts and ideas. You should try that this year and give us all some feedback this fall on how well it worked. Why havent we tried this before??

3/17/2011 1:45:04 PM

Ham Lake, Minnesota

That is normally the pattern I go with on my main plant and it's worked great both years. I choose to terminate the main at the pumpkin and use two secondary vines just before the pumpkin to achieve the same look as the drawing shows.

3/17/2011 2:23:35 PM

Johnston, Iowa

I have often wondered about this issue. Last year I lost my plant's stump (foamed and blew out) and some large/older secondaries due to borers. As such, I let the main and some new secondaries grow WAY past the pumpkin - probably 20 feet past is to make up for what I lost. I've never really understood if that was a good or bad move.

Joze, I think you're onto something here, and I like your pattern.

3/17/2011 7:36:22 PM

N.e. Ct.

Joze your info is very interesting,I like what I am reading.
A few questions:
1: If old leaves no longer provide sugar, is there a way to tell which one are to old and should they be removed?
2: If vine stresses can be managed logic seems to indicate that the pumpkin should be set as close as possable to the stump where the most developed roots are, your comments seem to support this yes or no???

3/17/2011 8:31:32 PM

Lloydminster/AB

A long time ago I noticed that when my plant was pruned my pumpkin slowed down. Pumpkins on plants that were slowed down by pruning sometimes picked up steam again after the plant had regrown. The fruit requires a mix of the main growth hormones in the correct rates to grow. When we prune we could upset the balance. Cut of all the tips and there goes the auxins and now the cytokinens are dominant. Maybe the plant gets root bound and the balance goes the other way. Not good. Right now I'm thinking that the pruning strategy may involve growing more plant after fruit set to help extend the growth curve. My initial thought is that closer to the crown would make it easier to grow more plant later. Interesting to see that others are witnessing the same things with similar conclusions.

3/18/2011 12:44:18 AM

Western NY

I've been doing a somewhat similar pattern as posted, because I stole the idea from Dan McKie when it was working well for him a few years back.

3/18/2011 9:27:18 AM

Deer Park, WI

Great question about the old leaves. I am unaware of any observable features that would indicate a leaf is no longer contributing photosynthetically. I'll keep this in mind as I plod along the path of plant physiology.

Equally intriguing question about pumpkin position on the main. I've given this much thought and have determined that there are many factors to be considered.

I'll reiterate sink/source relations one more time in the context of this question- Sources preferentially unload to the closest sink. Now, its important to recognize that the roots and nutrients/water they supply are NOT considered "Source" by definition of the word in plant physiology terms. Source is defined as an entity that produces "photosynthate", the sugar-water combination that ultimately fuels pumpkin growth. Thus, by formal definition, sources are healthy, mature leaves. Pumpkin position on the vine isnt as much a function of proximity to the most developed roots, rather, proximity to healthy, mature leaf clusters.

3/18/2011 9:36:09 AM

Deer Park, WI

Another quick refresher: xylem carries water from roots to the leaves. Phloem carries photosynthate from the leaves to the growing pumpkin. There's some connection between the xylem (roots) and the pumpkin directly, but its proposed that the majority (90%?) of the flow into the pumpkin is through the phloem.

No one will argue that by fruit set the most potent sources are the giant elephant ear leaves of those first secondaries. Having realized this, Chris, John, and I have been working hard to get as much foliage to maturity as possible by fruit set. Chris stated in his talk that we shoot for a minimum number of secondaries between crown and set rather than a measured distance.

Fruit position on the vine is a balancing act. I do not believe its coincidence that last year's WR was grown ~8ft from the crown. 8-12ft, if going by distance, seems to be the historical sweet spot. The most potent factor for me personally is the calendar day of fruit set. I want to maximize the number of growing days, especially up here in WI where the first frost can shut us down in early Sept.

I'll gladly take a June 23rd pollination 8ft out (8 laterals) over a June 30th pollinatino 12ft out if that means snagging another 7 growing days directly underneath the summer solstice. All that sunlight means photosynthetic machinery is working at its maximum. You cant get that back late season.

Great questions! Keep em coming-

3/18/2011 9:36:21 AM

Saegertown Pa.

Chris pumpkin was 8 feet from crown ? AGGC has it at 13 feet. Did you John and Chris all grow with the pumpkin in the middle of the plant ?

3/18/2011 10:51:51 AM

Deer Park, WI

Quinn- i should have better described the pumpkin I was referring to- Harp's 1725.

I'll defer to Chris on the exacts of his and John's fruit. I personally centralized the pumpkin on my two largest fruit. I had very ambitious post-set vine tips rolling into early september.

3/18/2011 11:35:57 AM

[email protected]

IIRC, Christy's 1725 was grown "christmas tree" style and she never terminated the main.

3/18/2011 4:37:37 PM

Massillon, Ohio

OK....let's see if I can get my thoughts to make sense! It has generally been believed that terminating vines will force the strength of the plant to the growth of the pumpkin. The old "we're not growing salad" idea! But you are saying that we need the vine tips for the growth hormone to keep the pumpkin growing. That led me to think about something else I've heard over & over.....that we should not terminate too many vines at the same time, or we risk the chance of splits, since too much strength will be forced to the pumpkin all at once!! (I'm probably not using the word "strength" correctly, but you get the idea!)
Is this just another unscientific falacy, if terminating vines doesn't really help the growth of the pumpkin? Anyway, Joze, will you comment on this? Thanks.

3/18/2011 7:22:48 PM

Lloydminster/AB

I'm just guessing though observations seem to support it that you still have to terminate vines but I would be terminating vines that are the farthest from the fruit. I think that the vines closer to the fruit should be allowed to grow much longer than 12 ft. I think this would be a spider pattern.My largest fruits have been grown on this pattern that I had to use due to the shape of my patch. I think that meets qualifications for stronger sink source relationship. This year I'm going to see if letting those secondary vines grow longer will make a difference. It will be really hard to tell without years trials though.

3/19/2011 12:49:02 AM

N.e. Ct.

Quote: "Phloem carries photosynthate from the leaves to the growing pumpkin. There's some connection between the xylem (roots) and the pumpkin directly, but its proposed that the majority (90%?) of the flow into the pumpkin is through the phloem."

Joze I hope this question dose not insult you. Is there some research data that supports the numbers in your above statment. Or does the word PROPOSED mean a best guess gut feeling?? I find it hard to beleave that 90% goes to the pumkin and that is a gut feeling on my part.
Dosn't the photosynthate fuel plant growth every where vines, roots, leaves, flowers, tendrels ECT.. as well as the fruit?
If one could generate a ratio between pkn weight and all other plant tissue weight, It seems loggicle that the pkn would only take that portion of the total fuel.
I don't beleave that a 1810 Lb pkn can be grown on a plant that weighs only 181 Lb's. I would love to read the reaserch data proveing me wrong.

3/19/2011 1:04:27 AM

Deer Park, WI

Finding balance between adequate vegetative growth and appropriate pruning is where the creative, artistic aspect of this hobby comes into play. Perhaps there is no "right" answer, only thoughts that seem to follow a logical premise.

The vine tips I am advocating for preservation are those found post-set. I remain firm in my belief that terminating vine tips pre-set is sound practice. I also believe that excessive pruning can potentially be detrimental, as a fully pruned plant will only have the pumpkin and the roots to allocate photosynthate to. This could create positive pressures/growth rates that lead to splits.

Returning to the diagram in my diary, by the end of the season I'd expect all vine tips to be pruned except for the main. This is a function of space and time.

3/19/2011 7:48:54 AM

Deer Park, WI

Firefly- not insulting at all. There are a couple of points that need to be clarified to provide understanding for your question.

Foremost, as a scientist, (officially by day, armchair by night), I qualify my own speculations as such and report fact and proposed theories as such too. Implicit in your message is an important consideration, clear delineation between personal opinion, research-based theory, and scientific fact is important when having these types of discussion. For the record, this discussion on pruning is my opinion, based on scientific logic. And the word "proposed", as used by myself, means science has published papers on the subject.

Secondly- the quote cited above is being misinterpreted. I am not stating that 90% of the photosynthate produced by the leaves is allocated to the pumpkin. I am stating that 90% of the nutrients/water that flow into the pumpkin enter by way of phloem versus the xylem. This has practical significance for the pumpkin grower because it may limit calcium flow into the fruit.

Lastly, there are indeed scientific papers that have explored the percentage of "phloem loading" versus "xylem loading" into the fruit. These studies have been done on a number of species of fruits and as a generalization, they have concluded that the vast majority (~90%) of the flow into a fruit is through phloem. Intuitively, this makes sense. Fruits tend to be sweet. Sugar is only present in phloem, not xylem.

3/19/2011 8:05:59 AM

N.e. Ct.

Joze thanx for the clarification, that makes a lot more sence to me. thanx for the great post and info. keep it up.
Do you have any insight on factors affecting seed quantity and quality, I have heard a lot of confuseing and conflicting info.

3/19/2011 8:33:19 AM

Ontario, Canada.

Indeed Joe you are correct as I have come across a few papers that refer to Xylem loading as you have described, 90:10 ratio

The best advantage a grower can give himself is the gift of young unsuberized roots. Young shoots & leaves with attached roots easily absorb and uptake nutrients. The only way to do this late in the season is as Joe has described.

The relationship of apical meristem signaling back to the crown I believe is a sound concept and can further delay senescence.

3/19/2011 2:35:55 PM

Ontario, Canada.

Joe, interestly I did do this on a 848* plant in 2006 that went down due to rib split. The main was still growing a few inches a day late in August. I believed it then and still do. I called it back feeding at the time. The main eventually reached to nearly 60' before the end came.

Backfeeding > Here is shot of the 848* extended main vine section running into the top of the compost pile. The pile is a mixture of Grass clippings, Leaves and Top soil. I'm giving only this section of the 848* plant IBA, 10-52-10 and Calcium to try and promote more root growth. Backfeeding with young unsuberized roots is what I'm after with this technique.

http://www.bigpumpkins.com/Diary/DiaryViewOne.asp?eid=55708

Good Luck & Good Growing

3/19/2011 3:10:03 PM

Garden State Pumpkins

I always love these posts....and I admit first off that I haven't seen your proposed growing diagram....but if I look back at an ancient HTGWCP 1,,,,Plant sizes were huge....As the trimming and pruning techniques improved pumpkin sizes have progressed. I believe the leaves do get tired as the season progresses. Maybe they have a sun light lifetime or chemical damage from over pushing but the early leaves do go away. If we still beleive that the 13 foot mark is the perfect mark...and first week of july as the time frame these early leaves have already spent two months on the vine. I have always agreed with the single sink idea from your earlier writings. Maybe you have hit on something by creating a new main to finish the season off. perhaps as the leaves go so do the pathways of the vine. and rather them trimming these close to the 12 foot mark we should allow further growth for a better ending in september. I worry that encouraging more vegatative growth we lose the window of pumpkin push were 70 percent of the pumpkin weight is put on early. Keep us thinking Joe.....I'll try to find the diagram you referenced. GrowEmBig! Chuck

3/22/2011 8:33:05 AM