How much NZN is too much?
Sprayed my pecans with a commercial NZN at a rate of 0.5 oz per gallon. The manufacturer suggested 0.2 oz per gallon. What negative effects will this have on my 6 year old trees?
Van Zandt County Texas
The original formulation of NZN was typically recommended at about 1 qt (32 oz) per 100 gallons of water, which converts to about 0.32 oz/gallon.
The original NZN was discontinued. There are some similar products and we find that the amount of actual zinc and nitrogen can vary by the product. I would rely on the product label as the appropriate guidance for dilution and spraying.
All that being said, if you apply too concentrated a formulation of zinc (too little water), you should see speckles or burned spots on the foliage. Perhaps marginal (leaf edge) burning could be seen. Such damage should not be considered severe--pecan trees can overcome foliage damage like this if otherwise healthy.
Zinc sprays should be made as you see new leaves developing. If no new leaves are observed, cease spraying until a new flush occurs. In large orchards of young trees, spraying every 14-21 days is advised due to the ongoing and random appearance of new leaves happening all the time in an orchard of that size.
Please contact me directly if you have further questions.