Muscadine vines stopped producing crops.

I have a 110' run of old muscadines that were planted about 1985 on a single wire trellis..  I have only lived here since 2006 and have been trying to have a good annual crop.  My first year pruning was very vigorous since they had not been pruned for about three years and there was a lot of old vines and dead wood to remove.

I have been having a good crop up until three years ago.  But since 2012 my crop has tapered off to almost no muscadines.  I am now getting very long new runners each year and also seeing more undeveloped 1/4" fruit as late as mid September, my normal picking time.

I have experimented with changes in  watering pattern, fertilizing, but nothing is helping produce more crop.  Three years ago I counted over 30 gallons of great muscadines that were produced.  I had so many after my family and friends had enough I put out road side signs and sold plenty.  in 2014 I only had 4 small ripe muscadines.

About four years before my crop tapered off to nothing, I planted a 30' row of various seedless grapes like Thompson and several other seedless varieties (I can't remember the names right now) that I purchased a my local Sam's Club.    The seedless? grapes are all loaded with seeds and are very tart even after four years of growth.
 
I also have a garden about 30' away that is about 130' X 40' that has stopped producing some crops like squash, and cucumbers.  The corn, beans, peppers, tomatoes are fine.  The lay-out is muscadines, then grapes, then garden.

So I am thinking two things, one- that the seedless grapes cannot coexist with muscadines, and two- I have seen almost no bees in the muscadines, grapes, and garden in the last several years.  I also do not use pesticides in the same area.

Even my neighbor about 1500 feet away is also not getting many muscadines.  He normally has enough to make annual wine.

My vines  normally produce large bronze and large dark purple fruit.

Do you have any recommendations about what to try to improve my muscadine no fruit situation?

Thanks for your help.

Also, great job on the three muscadine pruning videos. Thanks

Muscadine production depends on several factors including plant sex, pollen availability, pollen viability, pollination vectors, available nutrients, soil pH, disease and moisture. I won't go into great detail on any of these subjects, but will remark about how I think they might apply to you. I won't remark on pollen viability at all because it's too complex, and probably doesn't apply, anyway.

Muscadine varieties are either female or hermaphroditic. Female varieties do not produce pollen. Hermaphroditic varieties, also called "perfect-flowered", have both male and female flower parts, so they pollinate themselves and others. However, even "perfect-flowered" varieties benefit from cross-pollination. Since you and your neighbor both had good crops of muscadine grapes in the past, there must have been adequate pollen and pollination. If either or both of you lost grape vines, then you might have lost a source of pollen. However, I doubt this is your problem.

If pollen is available, muscadine pollination is achieved by insect carriers (vectors) and wind distribution. Insect carriers are most important. There are various opinions about which insects are most responsible for muscadine pollination. In my opinion, native wild halictid bees are most important. Regardless of which, pesticides can do damage to insect populations. Though you do not use pesticides in the area, keep in mind that other users might be reducing the pollinator populations.

Important macro nutrients include nitrogen, phophorus, potassium, calcium, magnesium, and sulphur. Important micro-nutrients include boron, zinc, iron, molybdenum, copper and manganese. Micro-nutrients elements become extremely important if they aren't present in sufficient amounts. Magnesium deficiency is very common in muscadine grapes. Boron deficiency will certainly reduce grape production. Magnesium deficiency will show up in a soil test, if you request a test for magnesium. Testing of leaf samples will indicate boron deficiency.

Even if present in sufficient amounts, most nutrient availability is reduced significantly if soil pH is too low or too high. Soil pH between 5.8 and 6.5 is best for muscadines. A soil test will indicate whether the pH needs to be adjusted, and tell how.

Mildew will impact grape production. Of course, high humidity contributes to the presence of mildew. If small grapes begin to form, but fall off prematurely, you might have a mildew problem. Fungicide application can help.

Now, here are some random but specific comments regarding your situation.

The presence of your seedless grape varieties have nothing to do with your muscadine grape production.

The absence of bees might account for some drop in fruit production in your muscadines, squash and cucumbers. But your corn, beans, peppers, tomatoes are fine.

Squash and cucumbers are prone to mildew infection. Since your muscadines, squash and cucumbers are not producing, perhaps mildew is your problem.

That brings me to what you said about "getting very long new runners each year and also seeing more undeveloped 1/4" fruit as late as mid September, my normal picking time." If you are getting very long runners, it's possible that you're applying too much fertilizer - especially nitrogen - and irrigating too much. Together, they can contribute to a rise in humidity and encourage mildew. That would also explain the late, undeveloped fruit.

To be brief, take soil samples from around your grape vines and vegetable garden to your nearby Cooperative Extension Service office for testing. In addition to macro-nutrients and pH, have them check for magnesium.

I expect you can stop fertilizing, at least this year. Don't irrigate unless weather conditions become very dry for an extended period of time.

I hope this helps.

Thanks for your compliment about the videos.


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