Melon Weed Management For Oklahoma

Weeds reduce profits in melon production due to the cost of efforts to control weeds and the losses that result from weeds that remain uncontrolled.   Weeds reduce yield and quality of melon crops and complicate other field procedures such as insect and disease management, irrigation, and harvesting.  Weeds may also provide cover for birds and mammals that damage fruit.  In situations such as non-irrigated watermelon production, weeds may result in yield losses by reducing soil moisture needed by the crop.

Weed management should begin at the planning stage of cucurbit production.  Practices useful for weed management include cultural (field selection, mulch, and drip irrigation), mechanical (cultivation, hoeing, hand pulling), and chemical (herbicides).  Selection of control practices depends on the specific weeds to be controlled, which may vary with site.  The planning process for melon production should include survey of fields to be used to determine what weeds to expect in the crop.  Your County Extension Office can assist with weed identification.  Avoid fields known to be very weedy or those heavily infested with difficult-to-control weeds.  Melon Weed Management Practices lists some weeds of Oklahoma that are often present in cucurbit fields and suggested management practices.  For information on the control of weeds not listed here consult your County Extension Office for assistance.   

Plastic mulch reduces the need for other control measures, except for nutsedge, which may penetrate plastic.  When using plastic mulch, weed control is needed at plant holes and at the edges of plastic strips.  Drip irrigation may reduce weed infestation by limiting the moistening of the soil surface to the area of the crop row.  However, wet weather may reduce this benefit.

Close cultivation and hand hoeing are usually performed before plants vine or begin setting fruit.  Cultivation should never be so deep or close to the plant that roots or vines are pruned.  Pruning slows plant and fruit development and reduces yield.  Root pruning may lead to blossom end rot in watermelon.  Roots may extend further than vines and are often very shallow.  Cultivation of row middles, often done with aggressive implements such as disk harrows, should be done with care to minimize root injury.  Crop root depth can be determined by sifting through soil at different distances from plants prior to cultivation.  Hoeing is useful for removing weeds that survive cultivation.  It may be especially important for difficult-to-control weeds that remain in the row after cultivation.  Hand pulling, in some instances, may be a practical means of removing large weeds and nutsedge.

Chemical control is often an important part of weed management in melon production.  Seldom will a single herbicide be effective on all of the weeds found in a crop.  For some weeds commonly found in Oklahoma, none of the selective herbicides approved for cucurbits are very effective.  Therefore, weed control in cucurbits is usually best achieved with a combination of cultural, mechanical and chemical practices.  When selecting herbicides, be careful to check for restrictions regarding grazing of crop residues, crop rotations and harvest intervals.  Herbicide Suggestions For Melon Production provides information on chemical control options.  Always check product labels for approved uses. 

Planting method often dictates which chemical control methods may be used.  With plastic mulch, chemical control is used mainly at the edge of and between plastic strips.  Postemergence grass herbicides are useful for planting holes and plastic edges.  For bare soil culture, many broadleaf can be controlled with preplant and preemergence herbicides.  Under cool or wet conditions, as often encountered with early planting, some herbicides may cause injury to germinating crop plants.  When using transplants, check herbicide labels carefully for application timing. 

Cultivation or other mechanical means are needed for broadleaf weeds that have already emerged.  For watermelon, a combination of cultivation and herbicides applied as a directed spray often provides good results.  However, wet weather may prevent timely cultivation needed with this method.  Use of preemergence herbicides reduces the need for cultivation, especially while crop plants are small.