What caused these squash and watermelon to be so tiny

Last year in one of my garden beds I had two plants runt out and produce tiny fruit. One was a sugar baby watermelon and the other was a Waltham butternut squash. All of the other plants of both types that I grew were normal in growth and fruit size. It was just these two individual plants that were stunted and produced stunted fruits.  If it had just been one plant of one species I would have just assumed that the one seed that grew into that plant had lost the genetic lottery, but two different plants of two different species growing within feet of eachother at the same end of a bed having the same genetic issue is unlikely.  I've used the same beds for years and never had this issue.  In the spring I amended all of the beds with the same compost and had automatic watering all season long.  Towards the end of the season I let weeding get away from me (essential worker picking up alot of extra shifts due to the pandemic) but that didn't cause any of the other plants to produce tiny fruit.  Both plants struggled all season, growing slowly and with smaller stems, flowers and leaves than their fellows growing just feet away.  The watermelon produced one tiny fruit and the squash produced four small fruit.  I didn't bother with harvesting the watermelon but I did harvest the tiny squash with the rest of the normal sized squash. I have eaten two of the tiny squash so far.  They were lacking in sugar (the normal squash from the rest of the plants are sweet) but it did contain what appear to be viable seeds.  The seeds are smaller, about 1/3rd of the size of the seeds from the unaffected plants, however.  I saved them separately to see if the plant was just a dwarf but thinking about that watermelon being so tiny makes me wonder if they were hit by some kind of herbicide that affects plants growth via hormone disruption.  The bed is just a couple of feet away from the property line.  Any ideas?

Did you look at the roots? Sometimes the soil conditions in one spot just aren't appropriate. Maybe there was a rock blocking root growth. Maybe that spot of soil was nutrient deficient. Maybe those seeds were as you suggest, not good in the genes.

Were they shaded out? Was water equally available?

There are tons of possibilities. Herbicide and other contaminants included.

Welcome tp Permies!
I am not very knowledgeable about squash or watermelons, but hopefully someone who is will chime in.
How is the light along the property line?
Is there a fence casting shade?

L. Johnson wrote:Did you look at the roots? Sometimes the soil conditions in one spot just aren't appropriate. Maybe there was a rock blocking root growth. Maybe that spot of soil was nutrient deficient. Maybe those seeds were as you suggest, not good in the genes.

Were they shaded out? Was water equally available?

There are tons of possibilities. Herbicide and other contaminants included.

I did not look at the roots, I just cut everything at soil level, weeded the bed and planted hardneck garlic.  I've gardened in the same spot since 2010.  The first few years I tilled the soil but had the garden at ground level. Since 2017 it has been more of a raised bed with dug out pathways between the planting areas.  So no rocks.  I add cow manure and compost every spring, fork it in and plant my spring vegetables. So I wouldn't expect it to be nutrient deficit.  I picked this spot for the garden when I moved in because it gets no shade, it is literally the sunniest spot on the property. The whole area receives water via a sprinkler.

William Bronson wrote:Welcome tp Permies!
I am not very knowledgeable about squash or watermelons, but hopefully someone who is will chime in.
How is the light along the property line?
Is there a fence casting shade?

There is a chain link fence and a grass lawn on the other side.  It doesn't cast shade on the garden.  I chose this spot to put my garden when I bought the property because it is the sunniest spot on my property.

I see, your elaboration eliminates a lot of variables.

Maybe Joseph Lofthouse or one of the other more proficient growers on the forum will chime in as William also hoped.

Tow options come into my mind.

Competition with Grasses and other weeds/veggies that take all the nutrients and/or bad prepared grow beds.

but more likely you are hit by a disease or virus that makes the plant weak and let the fruits rot.
Here is Google the best answer, look for all images and compare what you have.

Two pictures are not that much of a help to say what makes the leaves looking tiny and rotten in the second picture.

Is there any kind of herbicide or bovine medicine that could be in bagged cow manure that causes stunted growth in plants?  I put a few bags on each garden bed along with home made compost and work them in every spring.  If the bag that ended up getting worked into that end of the bed was contaminated it would explain the stunted growth from day one.  Or run off from some kind of spring weed and feed or herbicide used on the other side of the fence from that end of the bed.  I've grown in this exact spot, doing the exact same things for years and this was a first.  If it was a virus it would have had to infect them as seedlings and I would have expected it to spread to the other plants as the season went on. If it was a root feeding nematode or beetle larvae I would expect them to have spread from plant to plant as well.

Here's a pic of the soil without the weeds (when planting the squash bed to hardy garlic).  I've been improving it for years

I would consider squash bugs. They congregate on plants and fruits, and can be sneaky and hard to find mid-season when there is a lot of foliage. But, I've never done experiments or much literature research on the issue to be sure that little fruits are actually caused by them.

Hi Smith,
You've gotten lots of good suggestions and advice. Realistically, it could be any of these things. Are your neighbors spraying their lawn with anything? Weed killer? Contaminated bagged manure is a possibility. If that's the case the contamination will slowly dissipate over the next couple of years but you might want to add a pretty big helping of compost to that spot this summer. Could be bugs stunting their growth too. Lots of bugs like squash just as much as melons. I tend to agree that a virus or bacterial wilt would probably have spread during the season and been noticeable. Could be too much competition. The watermelon leaves looked pretty pale. Maybe could have used more nitrogen.

But I wouldn't rule out bad nematodes. In a town about 16 miles from me lots of people there  have a pretty bad nematode problem. So I always check the roots of every plant I pull up even if I am just going to turn over the dirt and leave them there. I usually plant one type of tomato plant, 6, 8, 12 plants, whatever, in one spot. Then I'll plant other kinds 20 yards away or so. 3 times in the last 11 years I have pulled up the tomatoes and found that just 1 plant or 2 next to each other have bad nematodes. They didn't infect the whole row, just a plant or two. So for those I always pull out every last little root and turn over that soil every day for a week or two so it seriously dries out. Then I cover it in plastic for the winter so it stays really dry until spring so the last of them die. That seems to work pretty well because it's such a small area. Once I didn't have time to do that so I just dug up the roots and poured a great big pot of boiling water all over that dirt. That worked too.

And spring is almost here! LET THE GAMES BEGIN!!

Herbicide contamination in the cow manure is a definitely possible culprit. There is a class of 'cides called aminopyralids that are used to control non-grass "weeds" in pasture. Things like dock, thistle. ragwort, blackberry, etc. are the targets. They are persistent in soil, don't affect grasses at all (but get taken up by them), are considered safe for grazing animals, and often end up in hay and livestock feed when they get applied to hay paddocks before cutting.

I'm not sure this is your problem, but I wouldn't rule it out either. When it's happened to me, it was in a truckload of stump grindings from a batch of elm trees that had been drilled with the stuff to kill all the root suckers. I had spread the material around lots of nut trees and mulched my hops patch with it. The tipoff that something was wrong was when I noticed the buttercup leaves were distorted -- badly curled and mangled as if they had been partially chewed. I raked it all up and moved it to a safe corner and still had a really bad year with some of the hazelnuts showing poor leaf development and no nut set, and the hops refused to put on any cones. Also, one volunteer pumpkin that started off great got mulched with the stuff and went into shock within days, then showed the same sort of distorted growth and set no more fruit after that.