Guide to the Commercial Production of Muskmelon (Cantaloupe) And

ALABAMA A&M AND AUBURN UNIVERSITIES Guide to the Commercial Production of Muskmelon ANR-974 (Cantaloupe) and Related Melons

Historical Perspective Muskmelons, often called can- taloupes in the United States, are not commonly grown here. True can- taloupes have deeply grooved fruit with a hard, warty, or scaly rind and B orange or green flesh. Muskmelons (Cucumis melo L. Reticulatus Group), on the other hand, possess a fruit Muskmelons produce two rind that is netted. The muskmelon is types of flowers:(A) Perfect a member of the Cucurbitaceae (cu- A flowers, having both male Note swelling and female parts, and (B) cumber) family, which also includes at base of flower. staminate flowers, having cucumbers, watermelons, and honey This will develop only male parts. dew, Persian, casaba, and crenshaw into fruit. melons. Flowers And Pollination Evidence suggests that muskmelons were cultivated in Egypt as early Muskmelons produce two types of flowers—perfect flowers, having both as 2400 B.C. Little information exists, male and female parts, and staminate flowers, having only male parts. Perfect however, describing how the plant flowers upon pollination and fertilization will develop into the familiar fruits. was used in ancient times. A native Muskmelons set fruit in cycles where several fruit are set per plant in each of Middle Eastern countries, musk- cycle. Fruit harvested from the first cycle of fruit set have the highest quality. melons spread slowly to Europe. In Muskmelons require bees for pollination. For greater yields and larger mel- the fifteenth century, muskmelons ons, place one or two strong hives of honeybees per acre adjacent to fields of became popular in Spain and were muskmelons. Hives can be removed after fruits are set. Application of pesti- soon introduced to the New World. cides should be delayed until evening when bee activity is low, as many pes- By the mid-1600s, muskmelons were ticides are toxic to honeybees. grown from Florida to New England. The modern muskmelon is derived Planting Recommendations from the ‘Netted Gem,’ a highly netted cultivar introduced by the W. Soil and fertility Altee Burpee Company in 1881. Muskmelons grow best on well-drained, upland, silty, or (preferably) sandy In the United States, muskmelon loam soils with a pH level between 6.0 and 6.5. Melons planted into acidic production is concentrated in arid soils (pH less than 6.0) will have yellowed foliage and produce fewer perfect and semi-arid regions, butARCHIVE they are flowers. Beds should be 6 to 8 inches high to facilitate drainage. If you use a grown in many states for local and cover crop, be sure to plow it under at least 1 month prior to planting. interstate sales. California accounts Timely and appropriate applications of fertilizer can make a significant dif- for 70 percent of total U.S. produc- ference in the quality and quantity of fruit and may promote earlier harvests. tion, followed by Texas and Arizona. Collect soil samples from each area you intend to crop and have a soil analy- Nutritionally, the muskmelon is much sis performed on each sample. Soil testing eliminates much of the guesswork higher in vitamins A and C than the involved in a fertilizer program. Be sure to apply lime several months prior to white-fleshed honey dew or winter planting. Contact your county Extension agent for information on how to col- melons (casaba or crenshaw). lect a soil sample and for boxes used to submit samples.

Visit our Web site at: www.aces.edu If a soil test is not performed, Varieties The following list of other types of apply 40 to 50 pounds of nitrogen melons are considered to be specialty and phosphorus (P O ), and 100 to Muskmelons generally are classi- melons in the United States, but they 2 5 fied as eastern-types or western ship- 120 pounds of potassium (K2O) per have similar cultural requirements to acre at planting. At layby, sidedress ping-types. muskmelons. Demand for these types with an additional 40 to 50 pounds of • Eastern-type characteristics: of melons tends to be regional but nitrogen per acre. Round to oval, usually sutured, and may offer a potential for smaller netted; not intended for long-distance growers or those who specialize in Seeding shipping. niche markets. Before considering Muskmelons may be planted by • Western shipping-type character- growing any of these melons, ex- direct seeding or by transplants after istics: Round to slightly oval, suture- plore the market potential of them in all danger of frost has passed. Direct- less, very well netted, with firm flesh. your region. Available commercial seeded melons should be sown Contact your county Extension varieties are listed following the de- when the soil temperature is above agent for the latest edition of the scriptions of the various types of mel- 65°F, but the optimum temperature Spring Vegetable Variety Trials from ons that follow. range for germination is between 70° the Alabama Agricultural Experiment and 95°F. Use fungicide-treated seed, Station, Auburn University. In the re- Honey dew as muskmelons are sensitive to port you will find information on the Smooth, greenish white rind, turn- damping off, especially under cool, performance of selected muskmelon ing creamy when ripe. Light green, wet, soil conditions. Sow seed at a varieties trialed in several locations sweet flesh with some orange fleshed depth of 1⁄2 to 1 inch. Seeding will throughout Alabama. As there are a varieties available. Fruit 7 x 71⁄2 inch- require 2 to 4 pounds of seed per large number of commercial varieties es, 5 to 6 pounds. Varieties: acre (16,000 to 20,000 seeds per available, only those well adapted to ‘Earlidew,’ ‘Honey Dew Green Flesh,’ pound), unless a precision-type seed- Alabama should be grown. It is advis- ‘Tam Dew,’ ‘Honey Dew Orange’ (or- er is being used. able to grow a small trial plot of sev- ange flesh). eral varieties each year to determine Transplanting which are best suited to your growing Casaba The use of transplants can reduce conditions. A non-slip (see Harvesting sec- seed cost compared to direct-seeding Many commercial muskmelon va- tion), late maturing, corrugated yel- and result in earlier production, espe- rieties are available with resistance to low, sometimes greenish yellow rind, cially when used with polyethylene one or more diseases, notably not netted or ribbed, with white, mulch. Seeding for transplant pro- Fusarium wilt, downy mildew, and spicy, sweet, and tender flesh. Fruit duction should be done 2 to 4 weeks powdery mildew. You should choose acorn-shaped, 8 x 7 inches, 7 to 8 prior to date of transplanting. varieties that are resistant to diseases pounds. Varieties: ‘Casaba Golden that are prevalent in your growing Beauty,’ ‘Casaba Sungold’ (earliest of Spacing and planting dates area. In addition, many muskmelon the casaba types), ‘Marygold.’ Whether direct-seeding or trans- varieties are sensitive to air pollution planting, space rows 5 to 6 feet apart (ozone, sulfur dioxide, and sulfur tri- Crenshaw with an in-row spacing of 18 to 24 oxide), as well as to applied sulfur Large, late maturing, yellow and inches. This will result in stands of (used for disease control). This sensi- green corrugated, rough rind without 3,600 to 5,500 plants per acre. tivity is cultivar dependent and may netting. Pinkish orange, sweet, tender Traditionally, in-row spacings up to be included in descriptions of vari- flesh with distinctive flavor. Fruit is 36 inches have been used in eties found in variety trial reports. elongated with a flattened stem end Alabama, but modern hybrids and (elongated acorn-shape), 9 x 7 inch- open-pollinated lines perform well at es, 7 to 10 pounds. Varieties: closer in-row spacings, resulting in ‘Crenshaw,’ ‘Honeyshaw’ (early), higher yields and increased uniformi- ‘Early Hybrid Crenshaw,’ ‘Crenshaw ty. Sow or transplant 20ARCHIVE March to 15 Blanco,’ ‘Golden Crenshaw.’ April in South Alabama, 10 April to 30 April in Central Alabama, and 20 Canary April to 15 May in North Alabama. Late maturing, bright yellow corru- Provide muskmelons with at least 1 gated rind. Flesh is pale green to inch of water per acre per week. white with a pale orange seed cavity; it has a sweet and distinctive flavor. Fruit is oval, similar to crenshaw, 8 x 6 inches, 6 to 7 pounds. Varieties: ‘Sweet Yellow Canary,’ ‘Tenerife.’

2 Alabama Cooperative Extension System Santa Claus Rochet ‘True Arus’ (yellowish green), aro- Very similar to Canary type except Green rind melons are slightly net- matic flesh; ‘Theresa’ (juicy green rind is mottled green and yellow. The ted and have greenish white, sweet, flesh); ‘Toho’ (green flesh). name is derived from the long keep- and aromatic flesh. Oval. Varieties: ing qualities of this melon. ‘Santa ‘Solo’ (4 to 5 pounds); ‘Toledo’ (also Mulching And Drip Claus’ is also the variety name. called frog skin type because of the Irrigation greenish yellow rind with dark green Charentais Polyethylene (black plastic) mulch blotches); ‘Verdol F1’ (dark green skin A popular European melon, also slightly netted and crisp, white, sweet can offer several advantages to grow- called ‘Chaca,’ ‘French,’ or ‘Italian flesh (resistant to Fusarium races 0, 1, ers. Black plastic mulch increases the melon.’ Smooth or slightly netted, and 2; also referred to as Spanish type). soil temperature earlier in the grow- gray-green rind with dark green, ing season, conserves moisture, and slightly furrowed sutures. Deep or- Chinese ‘Hami’ melon reduces several common problems: ange, firm, sweet flesh. Fruit is slight- Hami is the generic Chinese word soil compaction and crusting, ground ly elongated but mostly globe shaped for a group of crisp-fleshed “winter” rot of fruit, fertilizer leaching, drown- ing of crops, evaporation, and com- 31⁄2 to 4 inches and 11⁄2 to 2 pounds. melons. Hami melons may have ei- petition from weeds. These benefits Varieties: ‘Acor F1’ and ‘Alienor F1’ ther red-pink, salmon, white, or (both monoecious and resistant to green flesh. One group is slightly promote increased quality and quan- Fusarium races 0, 1, and 2), longer than a football but smaller in tity of fruit yields and result in earlier ‘Charentais Improved,’ ‘Ido,’ ‘Oval diameter (resembles Rochet type). yields, especially when used in com- Chaca,’ ‘Red Queen,’ ‘Panchito’ (net- These have yellow or yellow and bination with transplants. The use of ted rind). green rind, usually slightly netted. transplants with plastic mulch gener- The flesh is crisp and very sweet. ally results in harvests that begin 7 to Mediterranean These melons may be stored for sev- 14 days earlier as compared to bare Fruits have a green rind with slight eral weeks to a few months with little ground production. Although using netting with no sutures, ripening to quality loss. In China, these are even mulch will increase production costs, yellow gold with some green splotch- allowed to dry partially for use late those costs should be offset by in- es. Flesh is soft and white with a into the fall and early winter (similar creased profits from earlier and larger touch of pink around the seed cavity to Santa Claus melon). These appear yields. Drip irrigation systems must be used with plastic mulch. Be sure when ripe. Fruit oval 61⁄2 x 71⁄2 inch- to also be particularly suited for to offset the drip tape 3 to 4 inches es, 5 to 51⁄2 pounds. Variety: frozen melon balls. ‘Casablanca.’ from the center of the bed, 2 to 3 Oval, 6 to 9 pounds. Varieties: inches deep. ‘New Century,’ ‘Red-Pink Hami,’ Persian ‘Tiger-Skin Hami.’ Round type Very late maturity, green rind with Chinese Hami variety: ‘Snow Charm’ Row Covers And slight tan cracks or sparse netting. (better adapted to cooler areas). Fruit Windbreaks Orange-pink, sweet, firm flesh. Fruit can reach very large size (10 to 12 Spunbonded polyester and perfo- is round 71⁄2 x 8 inches, 5 to 6 pounds but more commonly 3 to 4 rated polyethylene row covers may pounds. Varieties: ‘Persian Medium,’ pounds), globe shaped, white to light be used for 4 to 8 weeks immediately ‘Crete’ (crisp flesh, excellent for yellow, smooth rind, light orange to after transplanting to further enhance frozen melon balls). pink flesh, crisp texture, sweet, ex- earliness. Covers should be removed cellent frozen. Ogen when plants begin to flower to allow proper pollination. Row covers may Melons are netted with no suture, Japanese melons be replaced after pollination is com- green, sweet, and have highly aro- These melons are extremely well pleted (after 3 to 5 fruits per plant matic flesh; the rind turns golden yel- netted, with green rind; fruit is non- have been pollinated) to further en- low as the melon matures. This slipping when ripe and very sweet. hance earliness. melon will slip like muskmelonARCHIVE and Round or slightly oval, about 7 x 8 Windbreaks are recommended resists splitting during periods of inches, 3 to 4 pounds. Varieties: where wind erosion is likely. rainy weather. Fruit is round, 3 to 5 ‘Tokyo King’ (the classic Japanese Temporary windbreaks of winter pounds. Varieties: ‘Galia,’ ‘Gallicum,’ type—white fleshed); ‘Emerald Jewel’ wheat or rye prevent sandblasting of ‘Haogen.’ (green fleshed); ‘Emerald Pearl’ young seedlings and whipping of (green crunchy sweet flesh); ‘Ginryu’ vines as plants begin to run. As with and ‘Zuikoh’ (both have sweet, green row covers, windbreaks also provide flesh, excellent frozen); ‘Amur’ additional heat accumulation in the (Persian type with light green flesh); spring.

Guide To Commercial Production Of Muskmelon 3 Weed Control Insect Control Whitefringed beetles A weed control program for any Several insect pests attack musk- Whitefringed beetles are named crop begins before planting, but this melon, and growers should be pre- for the white stripe on both sides of is especially true for muskmelons be- pared to make management deci- the adults. As with wireworms, the cause only a handful of herbicides sions regarding their control. Some soil-inhabiting larvae cause the most are registered for use on this crop. If of these pests may cause problems serious damage by feeding on the possible, select an area for planting every year, and others may only be roots of young plants. Larvae are pale where weed populations are low and occasional pests. Contact your county white to yellow, legless grubs with a there are no perennial weeds such as Extension agent for recommended in- dark head capsule ranging in size 1 1 nutsedge, bermudagrass, or vines. secticides registered for use on from about ⁄16 inch to almost ⁄2 inch Perennial weeds generally require muskmelons. Use insecticides only long. Severe whitefringed beetle in- powerful herbicides or fumigation to when necessary to conserve bee pol- festations can result in poor plant control. Primary tillage including linators and the parasites and preda- stands because of the destruction of moldboard plowing, disking, and tors of insect pests that may normally the root system by the larvae. As with bedding are considered weed control inhabit melon fields or adjacent wireworms, whitefringed beetles are methods, since these operations gen- areas. If an insecticide application is most likely to be a problem when erally kill most emerged weeds. It is needed, apply late in the day when melons are planted into new land. critical to start with a clean field be- bees and natural enemies are least But whitefringed beetles prefer a fore planting the crop, because any active. wide variety of broadleaf weeds (par- emerged weed will have a significant ticularly legumes) over grasses. If a advantage over the young muskmel- Wireworms whitefringed beetle infestation exists, on seedlings in competing for water, Wireworms are the soil-inhabiting the grubs can be detected in the fertilizer, and sunlight. larvae of click beetles. They have a spring before planting by turning over the soil with a spade. If grubs Cultivation can provide effective cylindrical, hard-bodied, wire-like ap- are observed, a recommended pre- weed control between rows as long pearance. They are shiny, brownish 1 1 plant soil insecticide treatment is war- as the cultivator can be used without yellow, and ⁄2 to 1 ⁄2 inches long. ranted. There is no available control damaging the crop. If plastic mulch is Wireworm damage usually occurs post-planting for whitefringe beetle. used, between-row cultivation may just after transplanting or seed emer- not be practical or may be limited gence. Larvae feed on the roots and Cucumber beetles because of potential damage to the stems of young plants, causing plants Two species of cucumber bee- plastic. Soil-active herbicides can be to become stunted and to wilt. Stems tles—striped and spotted—may infest applied before mulching, but the ef- may have shallow, oval feeding scars muskmelon. Both species are about fectiveness of post-emergence treat- or deep, circular holes where wire- 1⁄5 inch long with a yellow-green ments may be limited because of worms have entered. Wireworms are background color. The striped cu- plastic mulch. Hand weeding be- most likely to be a problem when cumber beetle has three black stripes tween rows may be a viable option melons are planted into “new” land along the length of the body, and the in small acreage situations. Contact (for example, pasture that contained spotted cucumber beetle has 12 black your county Extension agent for rec- grasses) or following plantings of sod spots on its back. In the southern ommended herbicides registered for or small grains. Damage is most often states, cucumber beetles may hiber- use on muskmelons. observed under cool, moist soil conditions and in heavier soils. There is nate during cold winters, or they may no “rescue treatment” for wireworm remain semi-active during warmer damage. If a wireworm infestation is winters. The beetles begin feeding on detected or suspected, a recommend- alternate weed hosts in the early ed pre-plant soil insecticide treatment spring and can move into spring- is warranted. planted melons just after seed emergence or transplanting. Cucumber ARCHIVEbeetle larvae feed on roots and stems and may cause stunting of small plants. When populations are high, the cucumber beetle adults feed on foliage and can stunt or kill seedlings or young transplants. Beetles also feed on melon rind later in the season, causing cosmetic damage that reduces the number of marketable fruit.

4 Alabama Cooperative Extension System Cucumber beetles also serve as Pickleworm majority will be located in the devel- vectors for the transmission of a bac- oping leaf tissue. Newly hatched lar- The pickleworm is one of the 1 terium that causes bacterial wilt, a most damaging insect pests of cucur- vae are only about ⁄8 inch long and serious disease of cucurbits. The bac- bits. This pest does not overwinter blend in with the green plant tissue, terium overwinters in the digestive north of southern Florida, but the but they can be detected with a bit of tract of the beetles and can be trans- adult moths migrate into the northern practice (a hand lens helps). Larval mitted to susceptible plants the fol- states as the growing season pro- treatment thresholds have not been lowing spring when the beetles be- gresses. Pickleworm moths are small, developed for pickleworm; therefore, come active. Transmission to plants about 1⁄2 inch long, and easily recog- the current recommendation is to occurs through wounds on leaves nizable by the wide, yellowish brown begin a weekly spray program with a created by feeding. Once infected, band on the outer wing margins. The recommended insecticide if any lar- plants become wilted and die. The body is also yellow-brown, with a vae are found on the plants. Growers only way to avoid bacterial wilt is to purplish tinge. The tip of the ab- who are not willing to monitor plants prevent the beetles from feeding on domen has a prominent rounded for signs of pickleworm usually begin the plant. Research at Auburn brush of long hair-like scales. The a preventive spray program when the University has shown that the first closely related melonworm moth (not flower buds first begin to form. A few weeks after beetles colonize the a serious pest) is similar in appear- successful cultural management strat- young cucurbit plants is the most ance, but the body behind the wings egy for pickleworm is early planting critical period for bacterial wilt infec- is silvery white rather than yellow- and harvest. As pickleworms are mi- tion. Therefore, this is the most im- brown, and the band around the gratory, large populations do not de- portant time to target cucumber bee- wing margins is narrower than that of velop until later in the season. This is tle controls. the pickleworm. particularly the case in central and north Alabama. There are two options for cucum- Pickleworm moths are night flyers, ber beetle control. If the area has a rarely seen during the day. Females Squash vine borer history of cucumber beetle and bac- lay egg clusters on tender buds and This insect is usually a greater terial wilt problems, growers may opt new leaves and sometimes on the problem on squash and pumpkins to use the systemic soil insecticide fruit. After hatching, young larvae de- than on muskmelon, but melons, par- carbofuran at planting. Research in velop inside the buds, blossoms, and ticularly in the home garden, can other states has shown that carbofu- leaf terminals. Older larvae are capa- sometimes be attacked. The adult is a ran may provide up to 4 weeks of ble of moving to the fruit where they “clearwing moth,” and actually looks beetle control. The other control op- enter and complete development. more like a wasp. The front wings tion is to monitor plants regularly, Damage from a single larvae boring are covered with metallic, shining, particularly during the susceptible inside a melon will make the fruit olive brown scales, but the hind early season stage, and to apply fo- unmarketable. The small larvae are wings are transparent. The abdomen liar insecticides if beetles are present. pale green with many black spots on is ringed with red, black, and copper, Pyrethroid insecticides will give the their upper surface; older larvae are and the moth flies swiftly and noisily longest residual control (about 7 a green-copper color except for the about the plants in the daytime. Eggs days). Foliar insecticides are not usu- brown head and brown area just be- are laid on stems near the base of the ally needed after beetle populations hind the head. decline and plants mature. plant. Upon hatching, the larvae bore Management of pickleworm with A new type of insecticide called into the stems and tunnel along, eat- insecticides can be difficult, because ing the inner tissue. Larvae are a Adios is now available for cucumber the larvae are almost always in pro- beetle control. Adios contains a bee- whitish cream color with a brownish tected locations on or in the plant it- head. tle feeding stimulant along with the self. The best management scheme is insecticide carbaryl. Beetles taste the to monitor plants weekly beginning feeding stimulant, feed compulsively when the first developing leaf buds on the insecticide, and die. Adios is a and terminals are formed. If present, fairly effective alternativeARCHIVE to standard young pickleworm larvae can be de- pyrethroid insecticides for control of tected by pulling apart the leaf termi- cucumber beetles. Another advantage nals or buds. Although larvae may of Adios over standard foliar insecti- also be found in flower buds, the cides is that Adios is not harmful to bees, which are important for pollination.

Guide To Commercial Production Of Muskmelon 5 As with pickleworm, control with In addition to feeding damage, weeks. Defoliated plants yield small, insecticides is not greatly effective, aphids can transmit plant viruses (for poor quality fruit. Mite infestations because the larvae are protected in- example, cucumber mosaic virus, wa- usually occur along the edge of a side the stems. Fortunately, this in- termelon mosaic virus; see section on field, frequently next to a gravel or sect is not usually a serious problem melon diseases for more informa- dirt road or a grassy area. Dusty con- in commercial melon production. tion). Control of aphids and aphid- ditions favor mite development. As Commercial growers with a history borne viruses are difficult with insec- mite populations increase, infested of borer problems usually watch for ticides. In fact, application of some leaves turn yellow. The undersides of moth activity around the plants, then insecticides like the pyrethroids de- affected leaves appear tan or yellow begin a weekly spray program with a stroys the aphids’ natural enemies and have a crusty texture. Mites can recommended insecticide if moth ac- and results in increased aphid popu- be identified by shaking leaves onto tivity is observed. A fairly effective lations. Therefore, use of pyrethroids a sheet of white paper and watching home-garden management strategy is should be avoided if possible. Over- for moving specks or by observing to check the base of the plant stems fertilization with nitrogen can also in- leaves with a hand lens. As with for holes or excrement, which indi- crease aphid numbers. Reflective aphids, pyrethroid and carbamate in- cates borer infestation. If infested, mulches can be used to delay colo- secticides may actually increase mite stems may be slit lengthwise at the nization by winged aphids and sub- populations by destroying natural en- point of attack and the larvae de- sequent transmission of viruses. emies of mites. Because mite infesta- stroyed. The stems may then be cov- Control of weeds within the field tions usually begin on the field ered with moist earth to encourage along field borders is also of value in edges, these areas should be inspect- development of roots. To reduce in- reducing the potential for aphid in- ed regularly, particularly during peri- jury the following year, all vines festation. Weekly application of high- ods of hot, dry weather. If a mite in- should be destroyed soon after the ly refined oils (for example, stylet oil) festation is found, the infested border final harvest. The soil should be using high spray volume and pres- areas may be spot treated with a rec- raked or disked in the fall and turned sure has been shown to reduce ommended miticide, followed by an- under deeply in the spring to prevent aphid-transmitted virus infection by other treatment within 5 days. the emergence of adults from co- as much as 90 percent. Continue to monitor the affected area coons. Mites are actually arthropods more to ensure that the mite infestation closely related to spiders than insects. does not spread. Aphids and mites They are tiny (about 1⁄50 inch long) Aphids are small, soft-bodied in- and pale yellow or red in color. A sects that feed by sucking fluid from hand lens is necessary to see them the plant. Infestations begin when clearly. They are primarily found on winged adults fly into fields from the undersides of leaves, where they weeds or other crops. Later, colonies suck plant sap and, in hot, dry of wingless aphids, which feed near weather, can defoliate vines in a few the plant base or on the undersides of young leaves, are produced on the plants. This feeding results in cup- ping of the leaves. When plants are Figure 1. Muskmelon infected with bac- heavily infested, leaf distortion and terial wilt. stunting are common, and fruit set may be reduced. Upper leaf surfaces Control Of Diseases may be covered with “honey dew,” a And Nematodes substance secreted by the aphids. The honey dew also causes stickiness As with any insect or weed prob- on fruit surfaces and is associated lem, always confirm your disease di- with the growth of black, sooty mold agnosis. Consult your county ARCHIVEExtension agent for recommended fungus. fungicides registered for use on muskmelons.

6 Alabama Cooperative Extension System Bacterial wilt from the vascular bundles. Then vector. Consult the Insect Control Bacterial wilt, caused by the bac- touch a clean knife blade to the cut section above for detailed informa- terium Erwinia tracheiphila, is a de- surface and slowly withdraw the tion on control of cucumber beetles. structive disease of plants in the cu- blade from the stem. Watch for a At the first sign of disease in small cumber family. Although bacterial white ooze that strings out in a fine plantings, wilted plants should be wilt is most common on muskmelon thread between the newly cut stem sprayed with a recommended insecti- and cucumber, it can also infect surface and the knife blade. cide and removed. squash, pumpkins, and a number of 2. Take two recently cut stem sec- Powdery mildew wild cucurbit plants. Watermelons tions from near the crown of a re- and most gourds are highly resistant cently wilted vine. Squeeze sap from Powdery mildew, caused by the to the disease. the cut stem ends then press the two fungus Erysiphe cichoracearum, af- ends together. Continue to squeeze, fects muskmelon, cucumber, pump- then slowly draw the two sections kin, and squash. The fungus pro- apart. The presence of a thin, sticky, duces a white to gray powdery white strand or strands between the growth on infected petioles, stems, two sections is a positive test for bac- and the upper surface of leaves terial wilt (Figure 2). (Figure 3). Crown leaves are usually Positive test results are easier to infected first. Severely infected leaves become yellow and then turn dry, brown, and papery. Infected plants may be stunted. The loss of foliage will increase the number of sun- Figure 2. Positive bacterial ooze test for burned fruit. Although fruit are not bacterial wilt. affected directly, severe leaf infection Bacterial wilt is characterized ini- usually results in reduced sugar con- tially by wilting and drying of indi- tent in fruit. vidual leaves. Within a day or two the wilting symptoms spread to leaves up and down a runner (Figure Figure 3. Powdery white appearance of 1). The bacteria spread from infected powdery mildew on upper leaf surface of runners to the main stem and then to muskmelon. other runners within the plant. Two diagnostic techniques can be used to obtain for cucumber and for some identify bacterial wilt in the field: squash than for muskmelon. Because 1. Cut a wilted stem near the the bacteria are spread by cucumber crown and squeeze sap from the cut beetles, the best and most logical Figure 4. Yellow spots of downy mildew stem, watching for a white exudate control is management of the insect on upper leaf surface of muskmelon. Table 1. Recommended Control Strategies For Common Muskmelon Diseases. Follow Use Balanced Scout Apply Allow for Destroy all Resistant Fertility for Recommended Control Good air Crop Varietiesa Programb Signs Fungicidec Weeds Movement Residue Rotationd Powdery Mildew √√√√√√√√ Downy Mildew √√√√√√√√ Anthracnose √√√√√√√√ Gummy Stem Blight ARCHIVE√√√√√√√ Alternaria Leaf Spot √√√√√√√√ Fusarium Wilt √√ √ √ aAlways use certified, disease-free transplants or seed. bFollowing a balanced fertility program includes conducting a soil test and following its recommendations. cAlways be sure to get good spray coverage, especially on the lower leaf surface. Apply fungicides on a timely basis. dRotate with non-cucurbit crops for a minimum of 2 years; minimum of 5 years with varieties resistant to Fusarium wilt. These diseases can be carried over from year to year on cucurbit weeds or muskmelon volunteers; thus, it is important to control weeds during rotations.

Guide To Commercial Production Of Muskmelon 7 The fungus can overwinter on Temperatures between 60° and Warm (75°F), wet conditions (fre- crop debris and, more commonly, on 70°F, heavy dews, or frequent rains quent rains, poor drainage) favor weeds. Spores of the fungus can be favor development. The fungus can rapid development and spread of the blown long distances on wind cur- overwinter in an area or can be intro- disease. Anthracnose can appear any- rents. Infected transplants can be an- duced on wind currents from consid- time during the season, but most other source of the disease. erable distances. See Table 1 for rec- damage occurs late in the season Development of powdery mildew is ommended control strategies. after the fruit is set. At least three favored by high temperatures (80°F) races of Colletotrichum have been re- and high humidity (50 to 90 percent). Anthracnose ported. See Table 1 for recommend- Development is also favored by lush Anthracnose, caused by the fungus ed control strategies. or poor plant growth (resulting from Colletotrichum lagenarium, can be a improper fertility), low light intensity, destructive disease of muskmelons Gummy stem bight and heavy dews. When conditions during warm, wet growing seasons. Gummy stem blight, caused by the are favorable, an entire field can be- The disease also attacks watermelon, fungus Mycosphaerella melonis, is a come severely infected within a cucumber, and gourds. common disease of muskmelon, wa- week. Powdery mildew, unlike most All aboveground plant parts are termelon, and cucumber. Symptoms fungal diseases, can be a problem susceptible to infection, and plants first appear as grayish green, circular during periods of dry weather. See can become infected at any stage in spots between the veins in the lobes Table 1 for recommended control development. Older leaves first show of leaves. Spots turn a dark brown to strategies. small, water-soaked or yellowish black with age. The leaf spot stage areas that enlarge rapidly and turn can be confused with anthracnose; Downy mildew tan to reddish brown (most cucur- however, gummy stem lesions are Downy mildew, caused by the bits) or black (watermelon). Spots are darker with target-like or zonate pat- fungus Pseudoperonospora cubensis, often circular to angular. Later, spots terns with less deterioration of the affects muskmelon and cucumber. may merge, blighting large sections leaf tissue. Spread of the disease be- The disease can reduce yield and of the leaf. These areas become dry gins in the center of the plant and fruit quality. If plants are infected and tear away, typically giving the fo- spreads outward. Lesions develop early in the season, downy mildew liage a ragged appearance. Often the first on the vines at the nodes and can kill plants. The fungus causes ir- leaves at the center of a plant are at- elongate into water-soaked streaks regularly shaped, yellowish to brown tacked first, leaving stems and run- that become pale brown to gray with spots on the upper leaf surface ners bare. Tan to black, elongated, time (Figure 5). Stem tissue often (Figure 4). Spots are often angular slightly sunken streaks (cankers) cracks and a characteristic gummy and are restricted by the small veins form on petioles and stems that can ooze exudes from the wound. of the leaf. Under moist, humid con- girdle the vine, causing death of the Infected vines and occasionally entire ditions, a fluffy, purplish to gray fun- tissue beyond the lesion. plants die. The disease, unlike an- gal growth appears on the underside Fruit, if infected early, may turn thracnose, does not attack fruit. of the leaf corresponding to the leaf black, shrivel, and die. Round, water- Although the fungi that cause spots above. As the spots enlarge, the soaked spots, 1⁄4 to 21⁄2 inches in di- gummy stem blight and anthracnose leaves turn yellow and eventually ameter, develop on the older fruit. are two completely different organ- die. Infected leaves that die remain Spots turn a dark green to brown isms, their spread and their control erect while the edges of the leaf with age and may become sunken. are very similar. Refer to the section blade curl inward. Severe infections Under wet conditions, pinkish col- on anthracnose for information on result in defoliation, stunting of ored spore masses can be seen ooz- the environmental conditions that plants, and poor fruit development. ing out of the sunken spots. favor their development. See Table 1 The disease usually affects older The fungus overwinters in debris for recommended control strategies. leaves first and progresses outward. from previous host crops, in seed, or ARCHIVEin weeds of the cucurbit family.

Figure 5. Gummy stem blight lesion on cucurbit vine.

8 Alabama Cooperative Extension System Alternaria Leaf Spot When the epidermis and cortical This fungus is common in soil. A Alternaria leaf spot, caused by the tissue (bark) on a section of the main wound caused by insect or mechani- fungus Alternaria cucumerina, af- stem is cut back slightly above the cal damage is necessary for infection. fects muskmelon and cucumber as soil line, a light brown discoloration The disease is more common in thin- well as other cucurbits. The disease of the vascular tissue (area just be- skinned varieties. Further infections causes damage by defoliating the neath the epidermis) will be evident. can occur during harvesting if knives vines and reducing fruit yield, size, Brown streaks may also develop ex- become contaminated through con- and quality. Symptoms first appear ternally on the runner at the soil line tact with infected plants or infested on the upper leaf surface as small, and extend for some distance up the soil. Control consists of management circular, tan spots with white centers. vine. Streaks are at first light brown, practices that reduce fruit injury, pre- Spots enlarge up to 1⁄2 inch in diame- turning yellowish tan, then dark vent fruit contact with the soil sur- ter, turn light brown, and form a brown with age. This symptom is di- face, or reduce moisture on the fruit slight depression. Spots on the upper agnostic for the disease. A white to surface. leaf surface often have dark concen- pink fungal growth may develop on tric rings within the lesions. Spots infected stems during wet weather. Mosaic viruses merge and defoliation occurs, begin- The causal fungus survives from Three viruses found commonly in ning with the crown leaves. season to season in old infected muskmelons are cucumber mosaic virus (CMV), squash mosaic virus Severe defoliation can increase the vines, on seed, or in soil. The fungus (SqMV), and watermelon mosaic number of fruit damaged by sunburn. can live on dead plant material or on virus (WMV). These viruses differ in Symptoms on fruit appear as circular, the roots and stems of other plants their host range, method of transmis- sunken spots. Spots may be covered such as tomatoes and several weeds. sion, and in how they overwinter. with a dark olive to green to black Infection occurs through the root tip, Symptoms produced by these viruses mold. Fruit turn brown and shrink, natural openings, or wounds (for ex- are similar, making field identification later becoming black and mummi- ample, nematode feeding sites), and impossible. Special laboratory testing fied. The rot is often associated with eventually the fungus invades the is required for positive identification. sunscald or over ripeness. water conducting vessels. Plugging of the vessels leads to reduced water CMV attacks more than 40 families The fungus can overwinter in or movement followed by wilt and of plants worldwide, including all on seed, in cucurbit weeds, and in death. Disease incidence and severity vine crops. Strains of CMV differ in infested plant debris. Spores of the are increased during warm, dry their host range, symptoms, and fungus can be spread by wind and weather. See Table 1 for recommend- method of transmission. Cucurbits rain. The disease is favored by warm, ed control strategies. are susceptible at any stage of wet (dews, rains, or overhead irriga- growth. When plants become infect- tion) conditions. Weak plants are Fusarium fruit rot ed in the six- to eight-leaf stage, most susceptible to the disease. See Fusarium fruit rot of muskmelon symptoms first appear on the Table 1 for recommended control is caused by the soil-borne fungus youngest, still expanding leaves. strategies. Fusarium roseum. Usually ripe fruit A mosaic pattern develops (healthy Fusarium wilt are affected. Lesions may occur any- dark green leaf tissue intermingled where on the fruit but are frequently with light green and yellow tissue Fusarium wilt, caused by the fun- found at the stem end. Tan colored (Figure 6). Leaves are often distorted, gus Fusarium oxysporum f. sp. melo- spots that are about 1 inch in diame- crinkled, curled, and stunted. Vines nis, only infects muskmelon, cren- ter develop on fruit. Internal decay may appear bunchy because of the shaw melon, and honey dew melon. may be shallow or may extend into shortening of the internodes. Plants infected early in their develop- the seed cavity. The rotted tissue is ment often damp-off at the soil line. white to rose colored, dry, and Older plants first exhibit temporary spongy. This tissue can easily be sep- wilting during the heat of midday arated from the surrounding healthy and generally die within a few days. tissue. A white mold develops on the Wilt symptoms develop ARCHIVEin one or surface of infected fruit during wet more lateral vines, starting at the tip. conditions and in storage.

Figure 6. Typical mosaic virus symptom on muskmelon leaf.

Guide To Commercial Production Of Muskmelon 9 In severe cases, older leaves may Root-knot nematodes die. Typical mosaic symptoms devel- Root-knot nematodes, op only on actively growing leaves. Meloidogyne spp., can attack cucur- When a plant becomes infected at bits as well as more than 2,000 other midseason, previous growth remains species. When root-knot nematode normal and produces healthy fruit. populations are high, plants are often Few fruit set on plants that are infect- stunted and may wilt during dry con- ed early in the growing season. Fruit ditions or during the hottest part of that do set, however, are often of the day. Nematodes damage the root poor quality and may be mottled Figure 7. Root galls produced by root- knot nematodes. system by disrupting the flow of green and yellow or have dark green water and nutrients and by causing warts. WMV overwinters in seed or in in- wounds that give access to diseases CMV survives in almost 800 fected weeds. In spring, the virus can such as Fusarium wilt. Detecting species of plants, including many be spread by many species of aphids root-knot nematodes in the field is weeds found in Alabama. These in a non-persistent manner. Later done easily by examining roots of weeds often act as reservoir hosts al- plantings risk greater damage as dis- symptomatic plants. The nematodes lowing CMV to overwinter. The virus ease incidence and aphid popula- cause knots or galls (Figure 7) to de- can be spread and transmitted by tions increase during the growing velop on both large and small roots; more than 60 species of aphids. season. knots range in size from the head of Transmission is in a non-persistent Control of mosaic viruses in cucur- a pin to 1 inch in diameter. manner, meaning that the aphids bits begins with eradication of bien- Root-knot nematodes have a wide only need to feed on a CMV-infected nial and perennial weeds and wild host range that includes many culti- plant for only a few seconds to pick reservoir hosts in and around gar- vated crops as well as many weed up the virus. dens and fields. Applications of in- species. The nematodes survive in SqMV infects most cucurbits but is secticides to prevent the buildup of the soil from year to year and be- rarely a problem in watermelon. On large aphid and cucumber beetle come active as soil temperatures in- muskmelon, SqMV causes yellow populations, as well as other insects, crease in the spring. The most effec- spotting, a green and yellow mosaic, will reduce virus incidence and tive control of root-knot nematodes is and green vein-banding on the spread. When possible, plant certified through the use of resistant varieties. leaves. A few leaves may become virus-free seed or transplants. Isolate Rotation with grasses and other ne- malformed with veins protruding be- later plantings far from earlier set- matode-suppressive crops (see yond the leaf margin. The virus can tings, especially if virus incidence Circular ANR-856, “Nematode overwinter in weeds, seed, and in was high. Removing infected plants Suppressive Crops”) or clean fallow- cucumber beetles. Cucumber beetles when symptoms first appear may re- ing during the off-season will reduce are efficient vectors of SqMV, spread- duce or delay spread of the disease. nematode populations. Soil fumiga- ing the virus during feeding. tion is an effective means of reducing WMV affects all cucurbits and a damaging population levels tem- few others including English peas porarily (one growing season). Soil and alfalfa. Symptoms vary depend- solarization has also been shown to ing on the host and plant age at the be effective in reducing nematode time of infection. Symptoms on most populations when environmental cucurbits may include stunting, leaf conditions are favorable for its use malformation, yellowing or light (See Circular ANR-30, “Nematode green mottling, and marginal chloro- Control in the Home Garden,” sis. Plants that are infected when Circular ANR-500A, “Alabama Pest they are young produce few mar- Management Handbook—Volume 1,” ketable fruit. Fruit that are produced and Circular ANR-713, “Soil Solari- may be dwarfed, mottled,ARCHIVE or spotted. zation for the Control of Nematodes and Soil-borne Diseases”).

10 Alabama Cooperative Extension System Harvesting Muskmelons need precooling The major quality factor in mel- soon after harvest to reduce field ons, soluble solids, is the sugar con- Muskmelons are harvested accord- heat in melons. Field heat is heat ac- tent of the fruit. A full-slip melon can ing to the degree of stem slip, which cumulated by the fruit growing in a have as high as 15 percent soluble is when the stem begins to separate field. On days with high air tempera- solids. Melons harvested at partial from the melon. Growers producing tures, internal temperatures within slip can have soluble solids ranging melons for local sale can harvest the the fruits will often be equal to the from 8 to 12 percent soluble solids. melons at full slip (when the fruit is air temperature. If field heat is not Soluble solids can be measured completely separated from the vine). removed, melons will degrade pre- quickly in the field with a hand-held At this point, the fruit has reached maturely, resulting in poor quality refractometer. To maintain the sugar full maturity and peak flavor, but will melons with a greatly reduced shelf content as high as possible, keep the soften too quickly for shipping. For life. Precooling can be done with foliage healthy by controlling foliar shipping, it is best to harvest when cold water, cold air, or ice. diseases, nematodes, insect pests, the muskmelons begin to slip, usual- 1 3 Hydrocooling is the most efficient and weeds. Also be sure to maintain ly “ ⁄2 slip” or “ ⁄4 slip.” Fruit harvest- method, but the choice among cool- a good fertilizer and irrigation pro- ed at this stage are not as soft, but do ing methods depends primarily on gram. not have as high a sugar content as economic factors and the type of those at full maturity. shipping container used. Buyers gen- Fruit are generally ready to be har- erally specify packaging and ship- vested 30 to 35 days following polli- ping requirements. Room cooling nation. Frequent or daily harvests are and forced-air cooling are also suit- necessary to ensure that melons are able for melons, but require more of good quality, especially if temper- time than methods above. atures are high at time of harvest. Room cooling is necessary after Assuming good cultural practices, precooling in order to maintain fruit one can expect to harvest 2,000 to quality. Muskmelons harvested at 5,000 melons per acre when grown partial slip can be held for up to 15 on bare ground or from 6,000 to days at 36° to 41°F at 95 percent rel- 12,000 melons when using plastic ative humidity. Muskmelons harvest- mulch. ed at full slip may be held for 5 to 14 days at 32° to 36°F at 95 percent rel- ative humidity.