squash and cucumber disease

[flashfyre]

Hi,

My squash plants are dying with a heavy coat of brown and white dust on their leaves. I think it's fungal?

Does anyone recognize it?

I am completely new at this.

Thanks,
John

[applestar]

I think those are some kind of sucking pest insects — white bits are probably shed skin, black bits could be frass (bug poop) or sooty mold growing on sweet honeydew excreted by the bugs. The images don’t focus completely so I can’t see — the blurry images look to me like green aphids. But likely pestswill depend on your location.

[flashfyre]

Hi Applestar,

Thank you, I took a closer look and found a leaf underneath that looks to have small green larvae all over it. I watched it under a magnifying glass and a couple of them wiggle once in awhile.

This is in Southern California.

Thanks
John

[imafan26]

Aphids for sure. I usually cut off severely infested leaves if the plant has enough remaining good leaves. I bag and trash the leaves.
Put out ant bait to control the ants. Aphids are not hard to kill but it usually requires thorough coverage and repeated treatments to get them all.

If it is not too hot (approaching 90 degrees), you can use any horticultural oil, but you must spray under the leaves and stems since it must make contact with the bugs.
Alcohol also works on lighter infestations, you do need to spray early in the morning so you don't burn the plants.
You can jet off the aphids with water. I will physically remove them from the leaves and if the ants are controlled they usually don't walk back on their own.
You can encourage beneficial insects. Ladybugs and their larvae as well as aphid lions consume a lot of aphids but you need to avoid toxic pesticides and give them time to work. It works best when infestations are not this bad.

Ultimately healthy plants are the best defense against pests. Pests attack weak and stressed plants, so keeping your plants healthy and happy, and encouraging a healthy garden patrol will control, but not eliminate most of the problem.

[flashfyre]

Thanks so much, off to the garden store in the morning. I've just finished reading about the aphid-ant relationship, I knew it from my school days and here it is!

[imafan26]

Another thing to remember is that aphids can transmit viruses as well. It is best to control them in the early stages before it becomes a major undertaking. When plants are severely impacted, they usually don't produce well, so I usually remove the plants and clean up the area well. I would usually try to plant somewhere else if possible. It might not have been the best place for the plant in the first place. The light, air circulation, plant spacing, and soil conditions may have contributed to plant stress. I have fewer problems with squash and cucumbers growing on a fence or trellis instead of on the ground. They get more light, better air circulation and they dry faster after it rains. They also take up relatively less space. Squash vines can get to be 50 ft or more and they go over trees, houses and anything in their way. Fruit is straighter and rots less when it can be off the ground.

[flashfyre]

It's my first try in decades. I helped my brother with his garden when I was a kid, that's about it.

I've made several mistakes and will be upgrading things over the next couple of weeks.

1) Lightweight wood trellis collapsed under 4 vines. A new one (steel, movable) is in work.
2) The sq. ft. garden grid and drip irrigation assembly are fixed to the raised bed and not easily removed. I need to rework this so I can expose the bed, break up and turn some areas (or all), amend, top off the soil, and then quickly reassemble everything.
3) Over-watering. A raised bed guide advised two medium waterings per day for the high desert of California, which works out to 4-5 inches per week on my drip system. The latest schedule waters 2x a week, to a total of just over an inch.
4) Failure to quickly address the aphid-ant farming. They hit the garden hard and fast. For the ants, I've had good luck with Terro liquid and custom bait assemblies in the past, usually the nest disappears within a week or two. The baits are already swarming with ants.

All I've got out of three months of effort are 3 ea. cucumbers and squash, although they were delicious. The garden was planted by seed and most of it never emerged.

In theory, the location is excellent, but it was the same guide that recommended the high rate of watering. It's a concrete 4x8 foot bed, 18" deep. It has southern exposure, with full sun for most of the day. The bed is filled with Mel's Mix, adjusted to a higher percentage of peat.

Many suggest soaking seeds overnight, plant, and germinate indoors, so I might do this going forward if my most recent planting doesn't poke up in a week or two. If anyone has seen a guide for raised bed gardening in arid, sunny environments please mention it!

Thanks
John

[jal_ut]

"The garden was planted by seed and most of it never emerged. "

I also have to ask: Where did you get the seed? Old or defective seed can be a problem too. Always get fresh seed from a reputable seed dealer.

[flashfyre]

Hi jal_ut,

I bought mine at Tractor Supply Company, labeled "Seeds of Change", "Packed for 2018", "Sell by Dec. 2018".

I wonder how many people end up with parts of their garden non-productive? I see a few channels on you-tube where the gardener has a large canopied growing area, many productive beds, and often ends up with a barren 2x4 or 4x4 -- they just seem to shrug it off -- "oh well, they didn't make it this year."

A few new items I'm pondering :

5) Add a canopy skeleton for hot streaks (part of the new trellis assembly). We had several 115F days this summer, as usual, and I see recommendations about throwing a 40% canopy over the top when the temps hit 95F or so.

6) According to my moisture meter the top inch or two are "dry", while 6-8" deep still measures "wet". I am considering a layer of mulch.

7) More water study. There seem to be two camps -- deep watering 2x - 3x a week, accumulating a bit over 1" of water a week, as contrasted with light watering every day, even multiple times on hot days. The "deep water" group is trying to push root growth, while the "frequent waterers" are looking to help cool the plants.

I can imagine a scenario where a lot of seeds did not germinate simply because the top inch or two was dry.

Watering is interesting to me since (some?) say, as long as 1" of water per week is met, and the moisture at root depth is in range, all is well. Seems very risky for germinating seeds near the surface, although the moisture is supposed to travel well in Mel's Mix.

Presumably drip irrigation design matters a lot -- I often read comments like "the soil felt dry so I hit it with 30 minutes of water". What does it mean? My own system has 256 emitters across the bed, implemented as 1/16" holes in the hoses, and pressure such that a 2-3" stream sprays from each hole. This yields about 1.75 oz. of water per emitter per minute. 45 minutes would be nearly 160 gallons over a 4x8 bed -- almost 8" of water in one go. Seems like a very important issue, as over- or under-watering is generally considered to be a bad idea.

Thanks everyone!

[imafan26]

Square foot gardening is a good place for a beginner to start. Mel actually, frowned upon automated watering in such a small garden. He recommended a good watering can. I would still use a hose since it don't want to have to walk back and forth to fill a can. I think one of the reasons he recommended hand watering because it made the gardener look at the garden more frequently. I water every day, while I am at it, I carry a ziploc bag with some salt in it and wear vinyl gloves. While I am watering, if I come across snails ( I do, every time), I either stomp on them or pick them off and throw them in the bag.

I have a wand on the end of my hose that has a 5 function tip and a dead man switch. I only use three functions. Shower, full, and jet. I use full to water large pots, shower to water most of the plants. While I am watering, I look at the plants, pick off bad leaves, they go in the bag too, I look under the leaves and if I see white flies, I use jet to wash them off. Any plant with sooty mold gets jetted.

I have a good garden patrol of geckos, frogs, cattle egret (comes by after I weed whack), lady bugs, parasitic wasps, and other beneficial insects. I put out ant bait whenever I see ants. I don't wait to see problems, because they will come in my house too.
Most of the birds I have are pests like the bulbul, mejiro and sometimes doves, so I have to put up bird barriers, cages and pick fruit at first blush. I rarely see aphids, but I do have other pests like scale on bay leaves, white peach scale ( I need to physically scrub it off, nothing kills it), and white flies are a problem every couple of years. Right now they are after the peppers. I jet water under the peppers every day to wash them off. It takes a while but they usually take the hint and go somewhere else.

Conduit (with a rebar core) or fencing posts make the best trellises. I use 6 inch concrete reinforcing wire for the trellis. For light vines, I can use cattle fence poss I just pound in the ground and use nylon trellis netting. As long as the trellis does not sag ( I need to wire a pole at the top of the cattle fences, the vines will actually create its own support. Nylon netting is all it needs and it is easy to slice it off and get rid of the vines when it is done. I have used the folding tomato cages for pepper supports. Stack two folding tomato cages to support cucumber or a few pole beans. If I open the tomato cage,I can use it as a short fence and train peas or beans on it.

In square foot gardening, you can get a lot of production in a small space by planting intensively. I actually don't plant anything big like peppers, eggplant. squash, or tomatoes in the main garden. I plant them in pots, because they take up too much space. I use the main garden for leafy greens, herbs, and corn in summer will take up the entire garden. I space most of the plants more than recommended because the sfg plan is a little too crowded for me and with all the diseases and pests I get, I need better air circulation. If you grow tomatoes in a 1ft sq space, you need to grow them on a trellis and prune off any leaves that go out of the space. If you only have a 16 sq ft garden space to tend to, you can take the time to work one square at a time and do the pruning and checking under the leaves almost daily. It is important when planting intensively, that you really keep on top of the problems because they can multiply quickly and spread from plant to plant.

[jal_ut]

"I wonder how many people end up with parts of their garden non-productive?"

I reckon everyone who plants a garden has these problems. Every year is different. One cannot predict the weather nor the bugs nor the critters. . You just plant it, watch it, tend it, water it, fix problems as they arise, (if fixable) harvest and enjoy! I plant a large garden and plant many varieties. I usually get a harvest of something, but rare is the year that it all comes on good.

[applestar]

It’s important to be aware of what time/months of the year are best for starting and growing which crop in your particular region.

Some things that won’t survive the super hot days of the summer will grow better in spring or fall and in areas where winters are mild, you can grow co weather crops through the winter.