I noticed some brown speckling appearing on the lower leaves of one one my plants this morning (my healthiest one until now 
), as well as some light specs on some upper leaves. Searching online for similar issues, I found spider mites, nutrient burn, and magnesium deficiency as some possible causes.
Can anyone help me narrow down the cause and fix?
The 4th photo (one from the bottom) favors the calmag deficiency. Im no means an expert do wait for other votes of confidence. But doesnt look like bugs imo. Have u been supplementing calmag in waterings?
I havenāt been supplementing with calmag specifically, just Biobizz nutrients mixed in tap water. My districtās annual water quality report notes about 0.6 mg/L of magnesium in the tap water, but I donāt know if that is an adequate amount for cannabis plants.
Me neither 
wait for the pros regardless. Im still fairly green myself.
After more research, I suspect CalMag deficiency. We have very soft tap water here, low in both magnesium and calcium (and probably iron too). Iām going to try some Sensi CalMag Xtra and see if that helps, unless anybody else chimes in with different advice.
Im only on 4th grow but i do know cannabis Loves calcium & mag & potassium! My girls scream for more & think thats what shes foing.Think the calmag will fix her up if not fill out support ticket & lets see whats going on.
Iāve been adding calmag to my water since noticing this issue, but it almost looks like the older, larger leaves are getting more speckled:
Maybe itās just the same leaves becoming more visible, as they grow taller and are easier for me to inspect, or that theyāre in starker contrast to the newer leaves around the buds, which are a very dark green, without any speckling.
For folks with more experience, does this look like calcium or magnesium deficiency? Our tap water (and the BioBizz nutes Iāve been using) are very low in both, so it seems like a logical explanation. Odd that it would only affect one of three plants treated identically, though.
hmm, just noticed similar speckling on leaves of a birch tree in the yard, as well as some holes in the leaves on that tree and on a variety of other trees and bushes. Maybe Iāve got a bigger problem than just my MJ nutesā¦ 
Im not so sure that looks like calcium deficiency. Have you looked for bugs?
Looked for them but havenāt seen any.
@Countryboyjvd1971, does this look like calcium deficiency to you? Im not sure.
Ot doesnt look like calcium to me my initial reaction was bugs also
@raustin and one of the leaves looks like something waas munching on it a good bug inspection may be wise
Other wise fill this out
COPY/PASTE the below list into your forum post.
Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so = NA
If you can, upload a picture of your plant. It helps the diagnosis, if needed.
Add anything else you feel would help us give you a most informed answer. Feel free to elaborate, but short, to the point questions and facts will help us help you 
Thanks!
@Countryboyjvd1971 I filled out the questions as best I could in my reply above and posted a couple pictures of the plants. I also took a closer look and noticed some more small holes on leaves of the two plants that arenāt showing any of the speckling/discoloration. Here are pictures of those:
I still canāt see any bugs on or under the leaves, though. When one of plants got some bigger holes in them earlier in the grow, which I suspected were from slugs, I sprinkled some Sluggo around the base of the affected plant and also sprayed some Dr. Earth Final Stop Snail and Slug killer spray around the base of the all the plants a couple hours after each watering for a while. I sprinkled some Spinosad dust on the affected leaves too and didnāt notice any more holes for a while.
Iām still not sure what exactly is causing these holes though, so Iād appreciate any insight you have. What, if anything, should I be doing at this point to keep it from getting worse? Iām reluctant to get any insecticides, even ānatural/organicā ones around the buds, as I really donāt want to be ingesting that stuff.
Thanks!
I had one bug chewing on all my plants last grow. Im indoor and luckily i was able to dispose of said bug. I definitely see chew marks and im with @PurpNGold74 i have seen the same thing in early grows at this stage and a more progressive stage and cal/mag was my answer. The diagnosing is a tough game, so many variables. Hope this helps One LoVe
This definitely looks like bugs. Keep a close eye out and maybe invest in food grade de. Its a white powdery substance that is a lovely preventative measure against many types of insects. Sorry i missd earlier. Didnt see and bite marks. But the last photos show something chewing. Look around daybreak/sunset. U may catch something. But ull need deterrence regardless
I had the same thing this past summer. It was spider Mites.
How long can i spray neem oil or dr earth final stop into flower?
I would never spray neem on buds, only leaves n in veg. And no idea about the dr earth product. Ill look into it
Edit: it says spray on foliage. I probably wouldnt put this on my buds neither. But again never used it. Someone may know better.
What do you suggest i do then? Idk what types of bugs but def bugs i have three plants going 1 photo about the end of week 2 flower week 3 starts monday and two autoflowers one lemon haze week 5 from seed starts tomorrow I start to see alot of pistols on top site one northern lights week 3 from seed no signs of anything yet the photo im morw worried about keeping good ive put DE in there for the second time today defoliated leaves and ive sprayed it with neem twice in the past two weeks and see less holes also brought temps down cuz ive been having a hard time dealing with heat and humidity with these heat waves leave were tacoing yesterday but seems when i fixed the heat issue leaves look better today the autoflowers got the most bites in them so they got there first DE today but since one has pistols idk what to spray for all of them or what to do at all sorry for the rant but thanks for your feedback
