Can someone help me diagnose the problem? Spots on the leaves. Beginner grower

[Damian]

Hello everyone!

First of all, this is my first post on the forum, and I appreciate all the help and participation from everyone here.

Summary of the Problem: As the title suggests, I’m a beginner grower and planted three Northern Lights auto seeds about three weeks ago. During the first two and a half weeks, the seedlings grew very well until spots started appearing on the leaves. These spots began as a lighter green compared to the rest of the leaves (possibly even a yellowish tone), and since then, they’ve gotten much worse.

Details of My Grow: I germinated my seeds using the paper towel method, and all three sprouted well. I then planted them in their final 5-liter pots around May 10th. After a week and a half, I applied a minimal amount of fertilizer. The instructions on my fertilizer say to apply it weekly, so that’s what I did. The plants continued to grow phenomenally for the next two and a half weeks until around May 27th-28th, when the spots began to appear.

After seeing the spots worsen, I searched online for potential causes and solutions. I read about nutrient deficiencies, incorrect pH, insect infestations, and fungal infections. My first step was to rule out sun stress, as I live in Madrid, Spain, and the sun can be quite strong in May/June. I initially moved the plants out of the sun during the hottest part of the day. When I didn’t see any improvement, I moved them to partial shade. Unfortunately, this didn’t help either, and the spots became more pronounced.

After thorough research and inspection, I noticed small webs, leading me to suspect spider mites. I bought neem oil and have been applying it every five days. I also considered that my plants might be suffering from nutrient burn (possibly from fertilizing too early), so I did a flush three days ago. I’ve since returned them to direct sunlight, and while I think the spots have stopped spreading, I’m not entirely sure. I need to identify the problem to save my plants.

Here’s a summary of my setup, pH, etc.:

• Strain: Northern Lights Auto
• Fertilizer: Top Crop Top Veg | Recommended dose: 2-4 ml per liter of water once a week | Applied dose: 1 ml per liter of water
• Substrate: Coco coir
• Pots: 5-liter plastic pots
• pH: Approximately 6.5 (I accidentally watered several times with pH 7)
• Watering: Twice a week (with foliar spray twice a day)
• Sunlight: 13 hours of direct sunlight (with indirect sunlight during the hottest hours)

Suspicions: Here are my suspicions in order of likelihood, considering this is my first grow:

1. Nutrient burn
2. Incorrect pH
3. Insect infestation
4. Fungal infection? (I haven’t taken any action against fungi yet)
5. Nutrient deficiency
6. Sun stress
7. Insufficient watering

Summary of Actions Taken:

1. Flushed the roots
2. Applied neem oil
3. Moved to partial shade during the hottest hours
4. Stopped fertilizing

I would appreciate any help. I think there’s still time to save them. I’ll attach photos below.

Thank you!

[NorseRow]

The color looks like they are lacking some nutes, the larger damaged area just looks like normal wear a tear, maybe from something rubbing against it or splash damage. The small white specs on the bottom leaves do look like the start of mite damage to me. But overall the plant doesnt look too bad really

[Borderryan22]

Did you mix the neem oil with water? Silly question, but it prevents large drops from pooling. The spots sort of look like spray

[OGIncognito]

I don’t really see an issue Growmie, that bottom leaf may have gotten wet?? The coco you’re growing in is void of all nutrients if it’s 100% coco and not amended. For the early growth stage their in make sure the coco stays damp and would be feeding around 500-600 PPMs at a PH of 5.8-6.2

[Damian]

Hi! Thank you so much for your response.

Do you suggest I keep applying neem oil for the possible spider mites issue?

[Damian]

Hi! Thank you very much for your response.

The neem oil I bought is in spray form and already contains water according to what it says on the label. I understand you’re asking this because you think the spray/water has acted like a magnifying glass?

I’ll attach a photo.

[Damian]

Hi, thanks for responding!

So, from your perspective, you don’t see anything serious?

Regarding your question about whether the lower leaf got wet, the answer is yes. Could that be the problem? If so, why?

Lastly, I don’t have a PPM meter, only a pH meter. I bought my fertilizer from a specialized cannabis cultivation store. On their website, they have clear instructions about the composition and usage. They recommend 2-4ml of fertilizer per liter of water. Could I rely on the quantity of milliliters instead of PPMs?

I’ll attach photos of the fertilizer and its composition.

To properly use this Top Veg growth fertilizer, it is advised to follow the manufacturer’s dosage recommendations:

1. Add 2 to 4 ml per liter of water when watering once a week.
2. Start with 2 ml and gradually increase the amount up to 4 ml.
3. Alternate these waterings with plain water.
4. When combined with other fertilizers, it is advisable to reduce the dosage.
5. Store in a cool, dry place.

Composition of Top Veg by Top Crop
Nitrogen: 9%
Phosphorus: 3.7%
Potassium: 7.7%
Humic acids: 3.8%
Fulvic acids: 2.6%
Boron: 0.1%
Copper: 1.018% chelated by EDTA
Iron: 0.16% chelated by EDTA
Manganese: 0.03% chelated by EDTA
Zinc: 0.026% chelated by EDTA

[OGIncognito]

This leaf looks like spill or damage from resting on wet medium.

@Damian

Could I rely on the quantity of milliliters instead of PPMs?

Personally I wouldn’t Grow Bro, a TDS pen is a critical piece of gear using synthetic fertilizer. It’s needed for mixing the nutrients at the right strength and also to measure the run off PPMs when needed.

@Damian

Composition of Top Veg by Top Crop
Nitrogen: 9%
Phosphorus: 3.7%
Potassium: 7.7%
Humic acids: 3.8%
Fulvic acids: 2.6%
Boron: 0.1%
Copper: 1.018% chelated by EDTA
Iron: 0.16% chelated by EDTA
Manganese: 0.03% chelated by EDTA
Zinc: 0.026% chelated by EDTA

Looks pretty good but missing calcium and magnesium 2 super vital secondary nutrients. Look into a calmag supplement and add with your base nutrients. Remember that coco needs and likes frequent fertigation or at minimum remains damp and feed to liberal run off

[Damian]

@OGIncognito

This leaf looks like spill or damage from resting on wet medium.

Ok I understand that being wet can cause damage, I will try to keep the leaves not wet.

@OGIncognito

Looks pretty good but missing calcium and magnesium 2 super vital secondary nutrients. Look into a calmag supplement and add with your base nutrients. Remember that coco needs and likes frequent fertigation or at minimum remains damp and feed to liberal run off

Awesome, I’ve done some digging on the calcium and magnesium supplement and got the one recommended by the seller along with the TDS pen.

One more thing, my fertilizer that I mentioned regulates the water pH to 7.0. I’ve always adjusted it down to 6.3. I’ll follow your advice to regulate the pH to 5.8-6.2, but here’s the thing: if the fertilizer adjusts the pH to 7.0 and I bring it down to 6, for example, will it lose its effectiveness?

[OGIncognito]

@Damian

if the fertilizer adjusts the pH to 7.0 and I bring it down to 6, for example, will it lose its effectiveness?

I might would agree with their claim if you’re growing in soil but with coco and daily feeding to run off the input PH wouldn’t have the time to change. Coco PH range is 5.8-6.2 and when you feed make a large circle several inches away from the main stem…this will get those roots to spread out searching for the nutrients

[BobbyDigital]

Im not seeing an issue. Those starter leaves are just that…starter leaves. The plant will discard those soon enough anyway. From the pics it looks like the plant may have variegation which is a genetic trait and not harmful at all or possible nute splash from pouring in your feed.