Weekly Express-News Article
Saturday, July 2, 2005
By Calvin Finch, Conservation Director and Horticulturist, SAWS

“Difficult Tasks for Summer”

            The Spurs won the NBA Championship and we all celebrated for the last week, but now it is time to come back to the real world.  Nothing is more “real” than our gardens and landscapes in July.  It is hot and dusty and there are some pretty unpleasant tasks to consider.

 

            Sandburs love July.  If you have the obnoxious weeds in your lawn or vacant lot it is time to spray them with herbicide before they produce the stickers.  MSMA works in a Bermuda, zoysia, or buffalo lawn.  Use glyphosate (Round-up and other products) in a vacant lot.  If the plants already have burs in place you can cut them low with the mower and then spray the foliage in a few days after it regrows.  If you are lucky enough to spray before the burs form recognize the plants by the fine grass like blades that are usually greener than the other plants. 

 

            The best way to control sandburs is to apply a pre-emergent herbicide like Amaze in March and again in June for two or three years.  For a detailed account of sandbur control visit the website plantanswers.com. 

 

            Webworms are ugly and very difficult to control.  The easiest way to live with webworms in your pecans is to avoid looking up for the next month.  If it is not in your nature to surrender, the best control is a spray of Bt (Dipel, Bioworm Control, Thuricide) on the foliage.  Your hose end sprayer may reach 20 feet at most so it takes a professional.  For a more moderate gesture, use a cane pole to open up the webs that you can reach.  The wasps and birds will eat a number of the unprotected caterpillars, but the sun is the most effective killer.  Outside of the web the worms fry in the sun. 

 

            Another task that qualifies as difficult is pruning out all of the old canes (floricanes) from your blackberry patch.  You must remove the floricanes to make room for the new wood, the primocane.  Recognize the primocanes by their vigor, large leaves and nice green color.  The floricanes have small browning leaves on canes that have quit growing.  Cut them at ground level and grind them in your brush chopper or bundle them for the garbage pickup.  The task is hot, thorny work.  Dress to protect your hands and skin.  Complete the work in the morning before temperatures are at their highest. 

 

            Chlorosis is a common recurring problem in San Antonio.  We have alkaline soil with a pH of over 7.0 and try to grow acid loving plants that prosper more readily in soils that have a pH under 7.0.  The pH of the soil describes its chemical characteristics.  One of those characteristics is that in soils with pH over 7.0 the iron is less available to plants because it is locked up in insoluble combinations.  The difficulty in uptaking iron is compounded when the soils are soggy, dry or cold.  A simple answer is to add iron; unfortunately it is not that simple.  The alkaline soils not only lock up existing iron, they are highly buffered, which means they have a huge chemical potential and can quickly capture iron that is added or overcome any attempt to acidify them.

 

            The only permanent solution is to use plants that evolved in alkaline soils.  Temporary solutions are to grow acid loving plants in containers or container like modified soils and/or to add iron on a regular basis.

 

            The product Ironite has not worked based on a number of tests in San Antonio.  Iron additives such as Sequential and Ferramec formulated as chelates work but are expensive.  Chelate means that the iron is connected to an organic molecule that keeps it from becoming locked up in our soil but it is in a form that can be used by plants.  You can make your own chelate by mixing one cup of iron sulphate (copperas) with a bushel of compost and using it as a mulch or soil enricher.  The fastest way of getting iron into your plant is to dissolve an iron source and spray it on the foliage.  Iron sulphate and the chelates work fine for this purpose.  Many fruit trees are showing chlorosis right now, the crop for next year is being formed so it is important to green them up with a foliar iron treatment.

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