Maleic hydrazide, better known as chemicals yet developed for modern gardeners.
Discovered accidentally by Naugatuck Chemical’s research scientists in 1948, MH has the unusual property of temporarily retarding plant growth without impairing the health of the plant.
The degree of retardation is directly proportional to the dosage sprayed on the plants.
In this writing, maleic hydrazide is being marketed under a half dozen different trade names for lawn use.
Using MH On Lawns
Properly treated grass grows much more slowly and thus requires less frequent plowings. On some experimental plots, only one mowing a season was necessary.
However, it is not recommended for lawns subject to heavy traffic—combining heavy traffic and retardation may kill brass completely.
But it can retard grass around the edges of all lawns, in areas adjacent to flower beds, under trees, and along fences.
In other words, it is to be used in little-traveled areas that are difficult to get at with the mower.
Effect Of MH On Plants
MH works in the growing tips, in the so-called apical cells of the plant’s stem, where it retards the division of cells.
Slowing down cell division, in turn, retards stem growth. The chemical is absorbed by green grass for about 24 hours after it is applied.
Once inside, it moves downward for about a week. It is less pronounced if heavy rains fall within a few hours after application.
The retarding of the growth rate takes place slowly. Hence gardeners should not expect overnight results.
For example, the effect of a slimmer treatment will not be readily apparent for nearly a month, whereas the results of a spring treatment are discernible within two to three weeks.
When And How To Apply
The best times to treat grass for optimum results are in the fall while the grass is still green (just before dormancy) and in April or early May.
MH can also be applied in summer, but at this season, the period of growth check is shorter than in spring or fall.
To permit maximum absorption, the grass should not be cut for a week after the treatment has been given.
After vigorous regrowth begins, the dosage for late summer treatment is 1 1/2 to 2 cups of 40% percent maleic hydrazide powder (MH-40) dissolved in 2 gallons of water for every 1,000 square feet of lawn.
Using Coinressedair Sprayer
A 3-gallon knapsack, coinressedair sprayer is best for applying it. Most of the experimental work with maleic hydrazide has been done along the Connecticut parkways, where more than 12 million square feet of turf have been treated.
The basic grasses in these tests were redtop. Chewing’s New Zealand fescue and Kentucky bluegrass.
In the Deep South, tests were made on Bermuda, carpet, and St. Augustine grasses. Slowing down the growth rate was also noted in the latter grasses.
Use Of MH Is Safe
On large turf areas along parkways and golf courses, hydraulic sprayers equipped with special nozzles and operated at 200 pounds pressure are used to apply MH.
Toxicological tests show that MH is a safe chemical, almost as safe as common table salt.
Cows fed on MH-treated grass eliminated the chemical, with none appearing in the milk. Therefore, there are no drift and sprayer contamination problems.
In other words, MH will not drift, damaging trees and shrubs nearby. as do some formulations of 2,4-D. And tire sprayer, following a thorough rinsing of lank and hose, can be used in insecticides.
Precautions To Be Observed
There are just a few precautions necessary with MH. It should not be used on newly planted grass areas, nor should it be used more than twice in the same season, even on well-established lawns.
Retreatment in the same season should be made only after normal grass growth has resumed.
Treatments must always be made on the green, growing grass. Finally, excessive doses will produce a temporary browning of the grass.
Other Unusual Properties
Another unusual property is its ability to control wild garlic, a weed spreading with alarming rapidity in lawns in the Northeast.
When sprayed on young, growing plants, MH moves to the growing point, where it stops the growth and tire formation of the ImIli.
Results are not apparent mail the season following the treatment because maleic hydrazide does not kill the current season’s growth but prevents the formation of bulbs, which give rise to the next season’s plants.
Controlling Number Of Weeds
MH also controls some other weeds, including knotweed, Johnson grass, pigweed, quackgrass, wild oats, and wild onion.
This chemical also keeps stored onions and potatoes at the prime quality for a long time, delaying fruit trees’ blossoming time.
As miss, late spring freezes and slows down the growth rate of certain hedges sufficiently so that they require trimming only once or twice a season.
New Cure For Leaf Yellowing
Sequestrene of iron, another interesting addition to the list of chemicals for the modern gardener, is proving more effective as a cure for chlorosis, leaf yellowing caused by iron deficiency, than the long-used iron sulfate.
It is especially effective in overcoming iron deficiency in ericaceous plants growing in acid soil, such as andromeda, azalea, and rhododendron.
Chlorotic plants growing outdoors should be sprayed towards the end of the growing season (August or September) with a solution of 4 level tablespoonsful of sequestrate iron to 3 gallons of water.
Results will not be immediately apparent, but complete greening of leaves should occur within six weeks to two months, and healthy growth should continue after the return to normal color.
Cornell research workers have found that botrytis infections on Croft, Creole, and L. Erabu floridi lily buds stored at 31° degrees Fahrenheit could be prevented by enclosing a small number of para dichloro-benzene crystals in the storage container.
Most Effective Against Crabgrass
Crabgrass is now flourishing in all its glory. This is the month when the chemicals potassium cyanate and phenyl mercury acetate can be used to the greatest advantage.
These chemicals are most effective against crabgrass and do the least damage to the desirable grasses if applied during a cool spell when the soil is moist.
They are apt to cause some damage to the perennial grasses, particularly fescues if they are applied during a hot, dry spell.
Resistant To Scab Disease
Dr. J. C. Walker and associates at the University of Wisconsin recently announced the development of two new pickling cucumber varieties resistant to scab disease.
The only other scab-resistant variety is Maine No. 2. developed at the Maine Agricultural Experiment Station.
A combination fertilizer-soil conditioner named Loma is now available for home gardeners.
Composed of Krilium and a 6.104 fertilizer, it is manufactured by the Tennessee Corporation.
Diazinon is a new organic phosphate insecticide developed by Geigy & Company, originators of DDT. It has given good control of flies in barns and has a residual activity of three months.
44659 by P. P. Pirone