I don't see any diseases, just a bit of nutrient deficiency (possibly magnesium).

I'm not familiar with Masterblend so can't really comment on whether that is an appropriate fertiliser.

Agree that there are clear signs of nutrient deficiencies in the photo. Cause could be several things. First, Masterblend is a hydroponic fertilizer and has very specific application rates and methods. It is not intended for use with soil-grown plants. Are these growing hydroponically (can't tell from the photo).

Second, using pesticides and fungicides where no need exists can interfere with nutrient uptake. So why are you using those?

Third, "watering well every other day" - why? Are they growing in containers? If so then perhaps the container is too small. Frequent watering flushes nutrients out of the soil so they have to be replaced just as frequently.

Dave

Thanks guys for the advice. These are grown in a grow box I had some masterblend remain so I decided to use it. I am thankful it's not a desiese. I will spray it with some epsom salts and see if it helps. Will update for the benefit of all.

While others are not very concerned, what I see is very troubling and likely more of a toxicity or pesticide injury problem. The plant is affected at the growth point and reversing that trend is hard to overcome. If the plant is important to to you then immediately transplant it to a "Clean" area and it may or may not recover.

Hi guys, first if all thank you all a million for your comments, greatly appreciated and helped alot. I believe it was a magnesium deficiency since the symptoms have now subsided. I did a water flush on the grow box and give epsomsalts in law doses at regular intervals. This helped. I bought a fertilizer for soil applications called blaukorn which is a slow release granular fertilizer. The plants are lookin better since and are improving. Im glad to have met you guys so I thought I'd share some of my container garden with you guys. Much love. All the best. Thank you.