spreading yellow spots - fungus? deficiency? bug damage?

Hi All,

Im growing an auto smurfberry (sagarmatha) and I am now 3 weeks in from germination. A few days ago I saw a bright green leafhopper and a fungus gnat (Iâ??m pretty sure it was one of those) sitting on the underside of the fan leaves.I didnâ??t manage to catch the leafhopper but I killed the gnat. A few hours later I checked and again saw the leafhopper which hopped away before I could kill it. So the next day I bought a pyrethrin based bug killer and killed off another gnat which was resting on the plant. Checked around the closet and sprayed another one in the act of scuttling off. The next day (yesterday) I percieved what I thought to be damage from the bugs and thought nothing of it â?? spots of varying sizes where it looked like the sap had been sucked out of the leaves. However, today I discovered that the spots are spreading and probably the ones I noticed first are becoming a much more distinct yellow. I have noticed no bugs at all today. Iâ??m also noticing what appears to be miniscule specs appearing on the newer leaves, but I canâ??t be sure.

After checking around on various forums, I think it is either fungus (could it have been spread from the gnat?) or a deficiency of some kind.

I have been using standard garden centre compost and watering every now and then when it gets dry. Although I watered it a bit more lately. No nutes at all given yet, and I have bio-bizz bloom ready for when it flowers. Should I be feeding it nutes now? On the packet it says there is enough nutes to sustain a plant for 4-6 weeks but I'm not sure if I trust that.

So what do you think?

Thanks for any help you can give me!

Fungus gnats do not usually cause fungus on plant leaves. The leaf hopper is the likely suspect, as they are sucking pests that puncture the leaf surface and suck plant juice. However, seems that you would be seeing a whole lot more of them if this is truly leafhopper damage.

A more worrying aspect of leaf hoppers and other "sucking" pests is that they carry and transmit plant viruses. Plant viruses are incurable and although they may not cause the death of the plant, the infected plant will then act as a vector for the virus to spread to all your other plants. I'm not saying that's what you have, but giving you info on pests and diseases they carry.

Fungus gnats do adversely affect plants (mostly very young plants) but not by marking leaves and not to any great extent that I can detect, unless the size of the population gets out of control. I do accept a certain number of gnats as a price to pay for growing in the summer, and I use passive controls which work for population control but not eradication.

Maybe I missed it in your post but are you growing inside or out?

Are there any signs of pests on the undersides of the leaves? Use a magnifying glass or something to look really good. Look for specks that move, or other unidentified matter.

Since you sprayed for critters the day before you noticed said spots, that could also be burn from spray.

You need to fill out the troubleshooting form. Folks will diagnose correctly if you will give them the info needed.

Good luck.

S=Answer if you grow traditional soil
E-indoor
E-soil,
CSL-Soil type/brand - Wilko multi-purpose compost
E-Water source Filtered water from a Brita Filter
E-Age of plant 3 weeks
E-Lighting source and distance from plant 28w neutral white flourescent 3600K (2010 Lumens), 3-6 inches (try to keep around 4)
E-Air temperature (both day and night if you are running a dark period) ~80-90 degrees Fahrenheit/ ~28-32 degrees Celsius
E-Air % Relative humidity not much humidity
E-Lighting schedule 24/7
E-Type of ventilation your room has extractor and intake PC fans
TR-Did you pre-soak your media in pH corrected solution? soaked in pre-boiled (then cooled) sterile water

Quote:

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Are there any signs of pests on the undersides of the leaves? Use a magnifying glass or something to look really good. Look for specks that move, or other unidentified matter.

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I will look with a magnifying glass in the morning, but looking very closely at all of the leaves and their undersides there is no sign of specs or anything moving.

Quote:

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Since you sprayed for critters the day before you noticed said spots, that could also be burn from spray.

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I sprayed under a leaf very precisely hitting the pest squarely. The top of the leaves did not get any liquid. I am aware that liquids magnify the light and can burn plants. I didn't cover most of what is spotted with spray. Unless the pyrethrin burnt it and I didn't notice I sprayed more than I thought, but I was pretty sure it would be non-toxic to the plant.

Some more pics attached. Notice the specs let light through and you can see the real colour of the light. [pics are much enlarged if you click them again to see the pics on their own in new tab/window]

Thanks for your help.

The first issue I see is the Brita water. No need to use Brita water, it does nothing to help your plant. Do you have a problem with your tap water? If not, use tap for irrigation.

The second thing that jumps out at me is there are no pH readings anywhere in your form answers. You need to check (and possibly adjust) the pH of your irrigation mixture each time you water. You can do this with either pH test strips or a pH meter, depending on your budget and how much you want to fuss with it.

You will need the supplies to adjust your pH up or down. This can be done multiple ways, depending on your situation. You'll have to do some research to determine what method may work for you.

I'm not sure what your Wilko soil has included. Does the package state there are added nutrients? It would be something like "plant food added", "feeds for 3 months", etc. At 3 weeks old, they may be wanting a bit of food.

You generally need two different nute formulas, one for green growing (vegging) and one for blooming. The vegging nutes are not as important as the bloom nutes.

These grow forums are packed full of searchable information. I would suggest you start with the FAQs and stickies. Good luck.

disregard this post

Looks to me like leaf-tip irritation. Happens when one leaf get's blown back-back-n-forth across nearby leaves, resulting in those little brownish spots. With the circulation fans pushing leaves back-n-forth, I've even see irritation spots that look like long, narrow bug tracks. Does look in the third pix (leaf with speclkes) like you sprayed with nutrients or ammendments without raising lights, but that too might be a leaf irritation situation. Sometimes the leaves get blown up-n-down instead of back-n-forth. No big deal. :jointsmile:

Everything else looks pretty good. Eventually, with the filtered water you'll want to add some source of calcium. I recommend unsulphured molasses.
Also, next transplant you'll likely want a lighter soil. Preferably potting soil with perlite. While you are out getting that...some more light wouldn't hurt at all.

Forgot to mention that likely you are ready to start half-strength veg nutes, and watch for reaction. Will be a while before ready for flowering nutes.