Weekly Q&A- Seth Nagy

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I was very glad to see the rain this week. Pastures and hayfields are shorter than normal when they started heading because of lack of rain. I hope this summer is not as dry as last year, but time will tell. Below are some questions that came into the Caldwell Extension Center. I hope you find these helpful for your garden and landscape.

Q: Someone told me I can change the flower color of my hydrangeas by adding something to the soil. Is this true?

A: Bigleaf, or French hydrangeas, can have either pink or blue flowers. Flower color is actually determined indirectly by the soil pH. Soil pH affects the availability of aluminum in the soil. In acid soils, the flowers will be blue, and in alkaline soils, the flowers will be pink. Aluminum becomes more available to the plant in acid soils. The flower color variation is due to the presence or absence of aluminum compounds in the flowers.

For blue flowers, maintain a soil pH between 5 and 5.5. Apply aluminum sulfate when you see new growth emerging in April, Aluminum sulfate will lower soil pH and also supply additional aluminum for the plant.

For pink flowers, a soil pH of 6 or higher is needed. Lime raises soil pH. Aluminum is less available when the pH is above 6.0. Turning flowers from red to blue is much easier than turning blue flowers pink.

Q: What “artist” bug is eating my magnolia leaves?

A: The damage to the leaf is symmetrical. This indicates the damage occurred before the leaf was fully emerged from the bud.

Magnolia leaf damage.

The symmetrical damage on this southern magnolia leaf indicates it occurred before the leaf emerged form the bud.

It also looks like the damage is not “fresh”. This is indicated by the brown margin around the damage.

What come to mind are three possibilities – beetles, caterpillars, or slugs. Beetles that might feed on leaves are not active this early in the spring. There are some looper type caterpillars that could be active in April, but typically these insects are seen by observant gardeners. By process of elimination, this leaves slugs as the likely culprit. Slugs come out at night and are often not seen by gardeners.

Since the damage is not fresh, I advise keeping an eye on the tree to see if more damage continues to occur before treating. Treating after the insect (or in this case the mollusk) has done the damage and left is not helpful in treating the problem.

Q: Can you recommend a self pollinating peach that blooms late? I have a peach that has had its blooms freeze for the last 3 years. No peaches. Lost the tag so I do not know the name. Nursery man said it was good for here. He was mistaken. I saw a reliance. I understand it needs 1000 chill hours. Would that suffice, in your opinion?

A: Site selection is as important as variety selection. Peaches need good air drainage to minimize the risk of late winter and early spring frost and freeze injury. Plant peaches on a slope. This will keep them from experiencing frost pockets that develop where cold, heavy air collects. Don’t plant next to wooded areas, windbreaks, or high hedgerows. These obstructions will impede air drainage, allow frost pockets, and increase shading that will reduce crop yield and increases the chance of disease. I suggest maintaining a distance of at least 80 feet from wooded areas or other obstructions.

Peach trees can withstand fairly cold temperatures (about -12°F). However, hardiness is affected by several factors. If the tree is late in going into dormancy, or hardening off, it will be more susceptible to cold winter temperatures. For example, excessive fertilizer in late summer can delay the onset of dormancy and increase the tree’s susceptibility to winter cold injury. Also, if a tree is cropped too heavily (fruit not thinned), its reserves are depleted and the tree may be susceptible to winter injury.

Bloom time for a given variety is determined by the length of the chilling requirement and the weather conditions in the spring. Chilling is fulfilled between 33°F and 45°F and is necessary for the tree to bloom and grow properly. Varieties that require 850 to 1,000 hours of chilling bloom later in the spring than those with a shorter chilling requirements. In Caldwell County, varieties with 800-hour to 1,050 chilling hour requirement do best.

Many great peach varieties have been developed in North Carolina through NC State University breeding programs. If I were to pick one variety to recommend in this case, I would pick Contender. This variety needs 1,050 chilling hours, it ripens in July, has large fruit, and it is a free stone variety. Contender is my pick, however, there are many other varieties that I’m sure can work just as well.

As always, for answers to your agricultural questions, call the Caldwell County Extension Center at 828-757-1290, or visit us online anytime at https://caldwell.ces.ncsu.edu.

Written By

Photo of Seth NagySeth NagyCounty Extension Director (828) 757-1290 seth_nagy@ncsu.eduCaldwell County, North Carolina
Updated on May 9, 2016
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