Are the high temps hurting melons?

cole_robbie(6)June 29, 2012

I have been having very poor setting of fruit on my muskmelon and watermelon this year. I wonder if it is the high temperatures and desert-like conditions that we have had.

Everything is the same as we have done in previous years: black plastic, drip irrigation, same varieties, and same piece of land. The land was not used last year. It's about half an acre, five 300 ft rows with a bee hive at one end. I know the drought is hurting the bees, but I think they are still there. I was stung as recently as about a month ago while walking by the hive.

The muskmelon leaves wilt in the day time, which I read is normal, but they are starting to die around the edges a little more every time. The watermelon plants look great and the vines are growing quickly, but there are just hardly any melons. The few melons I have range from tennis ball to volley ball size and look perfect, but there should be a lot more of them.

I can't find any relevant research regarding fruit set of melons in the very unusual weather that we have been having. It's 100+ all week with lows around 75 and 20% humidity during the day.

I have been turning on the irrigation almost every day for about an hour, as my grandparents always did before. The only thing I'm doing different is using a little brass fertilizer injector and feeding small amounts as I water. Lately I have been rotating miracle grow, Epson salts, and molasses. I would like to think the fert injection is responsible for at least having healthy plants and is not the cause of my poor fruit set.

If melons should still set fruit in these conditions, then all I can think to do is check on the bees. I did find a newspaper article from last summer that interviewed an Arkansas melon farmer who said that his melons almost shut down entirely above 95 degrees. That's the only thing I could find beyond the typical "melons love heat" advice.

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I grew watermelons and cantelopes in Austin, Texas for several seasons. They always had a decent set inspite of 100 plus degree days forever (Think 60 straight days or more) and really high night time temps. In fact I used to get bored in mid summer and start a second round of melons in July. That being said if your hundred degree days have come on all of a sudden then it may well have your plants in a bit of shock. My guess is however that if your vines are healthy as soon as your heat wave breaks a little your vines will start to set. Hopefully it wont be too late for a harvest.


    Bookmark   June 30, 2012 at 9:49AM
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Could be a soil chemistry issue, maybe brought on by the heat. Ca/Mg balance might be worth investigating since you mentioned you're applying Magnesium sulfate which you had not in the past. Too much fertilizing could be a problem if the plants are at all drought-stressed.

    Bookmark   June 30, 2012 at 11:05AM
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You might be on to something with the idea of "this soil" in "this heat."

The rates at which I have added the epsom salt is so low that it would be hard to imagine over-fertilizing. I've gone through only about a pound in the course of a month, which doesn't seem like much for 1,500 feet of melons. The ground did receive a broadcast granular fertilizer before we planted, but I looked it up and the rate we apply is much less than what I read is standard.

I don't have blossom end rot, thankfully. The flowers just dry up and drop off without growing a melon. I do have some Calcium Nitrate that I could feed through the drip line if it might help.

The soil is a mostly un-amended, light-colored clay. The only organic matter it gets it from letting the grass grow over it and tilling it in the next year. In the past, it was always fine. I wonder if the intense heat might be making the difference, and exposing the weaknesses of our unamended clay? There are some volunteer gourds that have come up in our adjacent patch or dying corn, and they look a lot worse due to not being irrigated. I don't see any gourds on them, either.

For next year, I am wondering if manure in the soil might help. I could also switch from black plastic to the white-on-black kind that is white on top and keeps the soil from warming so much.

    Bookmark   June 30, 2012 at 12:13PM
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fruitnut Z7 4500ft SW TX

It's not from the soil or air being too hot, melons love hot weather. Above 100F is not ideal for long periods but 90s are fine.

However melons don't pollinate well in hot dry windy conditions. And they must have bees for pollination. They only pollinate well right after sunrise in morning just after the flowers open. Wind and low humidity in early morning cause the pollen to dry up on the male flowers and the bees are less effective. I've found this out the hard way, by hand pollinating for many years.

    Bookmark   June 30, 2012 at 2:52PM
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Thanks. I have never seen the humidity this low. Normally, we have a heat index that is 10-20 degrees greater than the temperature. This year, the heat index has been typically lower than the actual temp, which I did not even realize was possible.

If I dragged a hose out and sprayed the plants late at night or just before dawn, would that help? Or would I just unproductively blast pollen everywhere??? It would of course go against the common wisdom that spraying water on leaves is a bad thing. I'm fine with spraying Daconil or other fungicide if I had to.

I have not checked on my beehive, but with the drought, it would seem like bees would be all over whatever flowers they can find. The catnip blooming in my front yard is full of bumble bees.

    Bookmark   June 30, 2012 at 4:14PM
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fruitnut Z7 4500ft SW TX


Spraying water won't do anything to pollinate. The male and female flowers are too far apart. There is nothing other than bees, or perhaps some other insect, to pollinate that many melons. Why not check your hive. Bring in another if possible. Each flower needs multiple visits for best pollination.

Last year we had humidity below 1% some afternoons, 15-20% first thing in the morning. I had real difficulty getting fruit set even by hand. This year on the good mornings I had too much set. The hail took care of that. But early morning weather makes a huge difference.

    Bookmark   June 30, 2012 at 4:41PM
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Thanks for the help. I am not looking forward to learning how to be a bee keeper. After I got stung, I read a little on the beekeeper forums. The drought seems to have caused a "nectar dearth," which made hives raid each other, which made the bees so defensive that they stung anyone walking near the hive.

    Bookmark   June 30, 2012 at 6:01PM
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