Plant in the spring, starting two weeks before frost. In fall, start sowing again six to eight weeks before your fall frost. Lettuce is cool-season crop that grows best in the spring and fall in most regions.
Plus, it grows great in raised beds and containers, making it ideal for small spaces, too. Lettuce is a great candidate for cold-frame gardening! Check out this video to find varieties of lettuce and salad greens that you can grow in containers for an urban garden!
Lettuce makes the perfect base for any number of salads. Try these eight great salad recipes with your harvest! I bought transplant lettuce at the grocery store established plants, ready to plant. They did well after I planted them in the planters, and doubled their growth. So, I decided to harvest it. But, I cut almost all of the leaves, including the ones in the center.
Did I kill my lettuce plants or will they regrow? Thank you for your insight! It depends how you harvested. If you cut off all the leaves with scissor at soil level, it will grow back in a few weeks. You may even get a third cutting. Seed more lettuce. But how do i make out 'before maturity' stage? You can start harvesting baby greens when they are 4 to 6 inches in height about days from planting. When you top harvesting is a judgemental call.
The leaves will taste bitter and the plant will look weak and no longer be producing leaves. How you harvest is up to you. You can use scissors and cut your lettuce off at the soil. And then the plants will produce new leaves from the base and can be harvested a seconod time in 3 to 4 weeks.
Or you can plant so that each head is 4 to 6 inches apart and harvest outer leaves or entire plants. Lettuce is healthier than you realize. It also provides Vitamin-A and Vitamin-K. It also has small amount of many other healthy nutrients. It is low in fiber and it has high water content. When harvesting outer lettuce leaves, is there a general rule of thumb regarding the amount that can be taken and how frequently? Hope my question makes sense. You can selectively harvest outer lettuce leaves before the plant reaches full maturity or as soon as the outer leaves are 2- to 3-inches tall.
You can cut or gently break off leaves as needed without harvesting the entire plant. Or, if the plant has reached the desired maturity, the entire plant can be pulled. I'm in a middle of a plight. I'm leading a research work in order to investigate the transmission of hereditary information from the lettucce.
In order to do so, I need to isolate one factor, such as light , salt or humidity; modify it according to the amount and analyze the difference between two generations.
It's been troublesome lately, and I was wondering if you would be so kind to help me. I am harvesting them outwards, where sun light is always upon them. I need you to tell me how much amount of water a lettuce can withstand without dying, the minimum, the common and the utmost. I would also appreciate whether you would be able to do the same with salt. In our country, we are facing problems about harvesting Iceberg Lettuce because of uncertain weather. Base on your experience at Farm, what is the best time to harvest this type of Lettuce?
Some say that the harvest must be done before sunrise. Kindly need your information. Raised vegetable beds Zone 5. My wife says watering in heat of day full sun bad for vegetable leaves if water covers the leaves. I use a medium spray garden hose.
Drip irrigation not an option - at least this year. On some smaller plants carrots and narrow leafed lettuce the plants do tend to mat down - but spring back as sun helps evaporate water. Should I switch to watering can and avoid watering plants directly?
I did read in comments that keeping soil moist is good - at least for lettuce - I may need to water twice a day? Thank you. Lettuce is delicious and does help with stress! I point out that natural rainfall is indiscriminate!
Just look at it. If the leaves are wilting, sprinkle them anytime—even in the heat of the day—to cool them off and slow down the transpiration rate. So, not necessarily twice per day. Have you tried a hose without the spray nozzle: laying it down on the soil near the plants and soaking only the ground that way?
It is labor-intensive, especially for harvest and post-harvest handling and packaging. The U. Department of Agriculture USDA prohibits discrimination in all its programs and activities on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or family status.
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Value Added Producer Grant Recipient. The bolus implement consists of two chisels situated about 3 inches of the center of each furrow to breakup the soil pan. The chisels are followed by a wedge to move displaced soil back onto the sides of the furrows, then followed by a large steel wheel to pack and shape the furrow. Approximately 14 days following the first cultivation, near early head formation, a second series of spiking, sidedressing and bolusing is often performed.
Economic losses due to weeds can be a serious problem in the production of lettuce. With planting taking place from late August through December, summer annual, winter annual and perennial weeds may be a problem. Weeds decrease crop yield and quality through competition for water, nutrients and sunlight. In addition, many weeds harbor destructive insect pests and serve as alternative hosts for other organisms which cause crop diseases.
Weeds commonly encountered in lettuce in Yuma, AZ in the late summer plantings include summer annual grasses such as watergrass or junglerice Echinochloa crus-galli or E. And groundcherry Physalis wrightii In the transition period between hot and cooler temperatures, lambsquarters Chenopodium spp.
And cheeseweed Malva spp. By late-October when temperatures cool, winter annual weeds are prevalent. Winter annual grasses include canarygrass Phalaris spp. And volunteer small grains. Cruciferous weeds such as London rocket Sisymbrium irio , shepherdspurse Capsella bursapastoris and black mustard Brassica nigra are commonly encountered. Lettuce-related weed species are also prevalent under cooler conditions, including prickly lettuce Lactuca serriola and sowthistle Sonchus oleraceous.
Cultural and chemical technologies are utilized for weed control in lettuce. Cultural practices including mechanical cultivation and hand hoeing are utilized from the fallow period prior to seed bed formation until first layby.
Herbicides have been used for weed management in lettuce for more than 30 years. There are four distinct timings of application for herbicides in lettuce: fallow, preplant, preemergence and postemergence. Before seedbed preparation, Roundup Ultra glyphosate , applied at 0. Fields are laser leveled and then flushed with water to germinate weed seeds. These broadspectrum non-selective herbicides are applied after sufficient weeds have emerged.
After a field has been laser leveled and prior to listing the seedbeds, Balan benefin , at 1. Per acre, is commonly applied and disked into the top 4 to 6 inches of the soil. Balan controls some grasses and some small-seeded broadleaved weeds Table 1. Balan moves very little in the soil profile or within the plant tissue. Table 1. Efficacy of preplant and preemergence herbicides against commonly occurring weeds in lettuce. Kerb pronamide , at 1.
Per acre, can be used preplant, preemergence or postemergence. However, most applications are applied banded over the top of the seedbed just before or immediately following planting. These preplant and preemergence applications should immediately be followed by sprinkler irrigation of 1 to 2 inches. However, Kerb is sensitive to movement in the soil with water, and excessive sprinkler irrigation will leach the material out of the weed seed zone top 1 inch of soil and render the product ineffective.
Thus, the effectiveness of Kerb is greatest if used on lettuce that is not sprinkle irrigated. For postemergence applications, apply before or after lettuce emerges, but prior to weed emergence.
Kerb is most effective against cool season annuals, and best fits lettuce planted after September Table 1. Prefar bensulide ; at 5. Prefar is most effective against summer annual weeds, and is most efficient in lettuce planted in August and September. Preplant applications should be mechanically incorporated 1 to 2 inches before planting. Preemergence applications should be immediately followed by irrigation.
When incorporating using sprinkler irrigation, wet the soil to the depth of 2 to 4 inches. Furrow irrigation should thoroughly wet, or "blackened," the top of the bed. Prefar moves very little in the soil and should stay within the weed seed zone. Prefar can also be applied through sprinkler irrigation. Maximum weed control using preplant or preemergence herbicide is best achieved if the herbicide can be concentrated within the weed seed germination zone top 1 to 2 inches of soil.
Additionally, a smooth, clod-free surface will maximize weed control when using Kerb or Prefar. Combinations of Balan and Kerb control most weeds. Use Balan preplant incorporated followed by Kerb applied preemergence and incorporated by irrigation , or apply both herbicides preplant and mechanically incorporate.
Weeds related to lettuce such as prickly lettuce and sowthistle are not controlled. Other difficult to control weeds that may occur in lettuce include horseweed Conyza canadensis , fleabane Conyza bonariensis , cudweed Gnaphalium palustre , groundsel Senecio spp. And broadleaf perennials and nutsedges Cyperus spp.
Balan, Kerb and Prefar can cause injury to lettuce, especially under environmental conditions where lettuce emergence is slowed. Also, some lettuce varieties are more prone to injury than others.
Refer to the herbicide label for details. Poast sethoxydim used at 0. Per acre with a crop oil concentrate added will selectively control most annual and perennial grasses found infesting lettuce. Timing is critical for optimal control; apply Poast when grasses are small.
Do not apply to grasses under stress. Thorough coverage is required. Do not tank mix with other pesticides as efficacy may be reduced.
Do not cultivate within 5 days prior to application or within 7 days following application. See the label for specific directions. There are many insecticides registered for use in lettuce, more than can be adequately addressed in this document.
Refer to specific insecticide labels for details. Field crickets Gryllus spp. Description and Life History: These insects are annual pests in early planted sprinkler-irrigated lettuce fields in the low desert. When they occur, they can quickly destroy most of a field. Problems are usually in fields planted closely to cotton or Sudangrass in August and September. Moving out of cotton, Sudangrass and desert flora, large numbers of these pests will migrate to seedling lettuce if available.
Most damage occurs at night. They hide during the day in soil cracks, ditches, weeds, and under irrigation pipes. They are similar in appearance to many ground beetles. Darkling beetles normally have the tips of their antennae slightly enlarged, while ground beetles antennae are not enlarged on the tips. Ground beetles are predators feeding primarily on other insects.
They have very short elytra covering their wings, but their abdomen is not covered. Rove beetles are often confused with winged ants or termites. When disturbed they will elevate their abdomens similarly to a scorpion. Rove beetles are insect predators or scavengers feeding on debris in the field.
Damage: Cricket and darkling beetles will destroy a crop by eating the newly emerged seedlings. Although ground beetles and rove beetles do not feed on the plants and are usually considered beneficial insects, they often damage fall vegetable crops by digging and rooting up the seed and small seedlings. Management and Control: These insects are difficult to monitor.
Early-planted lettuce in close proximity to cotton or Sudangrass should be considered high risk fields and should probably be treated as soon as the seed begins germinating. Apply baits around field edges to control migrating populations and apply insecticides through the sprinkler pipe during germination and when the plants emerge.
Scout the field by looking under the sprinkler pipe to determine if control was achieved or if re-application is necessary. Description and Life History: Saltmarsh caterpillars are not normally a pest of fall grown vegetables but will often migrate as larvae from neighboring cotton or alfalfa.
Large populations can be extremely damaging to seedling lettuce. The larvae are usually yellowish brown in color and covered with long, dark black and red hair. Many people refer to them as wooly bear caterpillars. Full-grown larvae may be 2 inches long. Adult moths have white to yellowish wings and are peppered with many black spots. Their wing span is approximately 2 inches Eggs are laid in clusters of 20 or more on the leaves. Damage: Most damage occurs to early planted seedling lettuce.
Large populations of larvae will move out of newly defoliated cotton and devour the young plants. After thinning, saltmarsh caterpillars are generally not a problem. However, they should be included in counts for Lepidopterous larvae. On older plants damage is distinctive. They prefer to feed in groups and will completely skeletonize several adjacent plants. Management and Control: Scout adjacent cotton fields prior to lettuce emergence. It is best to control saltmarsh caterpillars before they enter the field.
If possible treat the population in the cotton field during or just before defoliation. Saltmarsh caterpillars are particularly sensitive to Bacillus thuringiensis B. Physical barriers are effective at preventing larvae from entering a field.
Saltmarsh caterpillars do not like to cross fence type barriers of aluminum sheeting or irrigation pipe. These devises can be used to herd populations into holes containing cups of oil. Ditches filled with water containing liquid detergent or oil are also effective. Carbaryl can be sprayed around cotton fields or along ditches to kill migrating populations.
Description and Life Cycle: In the Southwest, the sweetpotato whitefly is one of the principal pests of crops Fig. It was not considered an important pest until the early 's, when extremely large populations became common on cotton, melons and lettuce throughout the Southwest. In a short period of time, the sweetpotato whitefly shifted from a position as a secondary pest to being the primary pest for fall vegetables.
This shift in pest status is thought to have occurred due to the introduction of a new strain of sweetpotato whitefly B-strain.
The B-strain is also known as the silverleaf whitefly. The host range of the B-strain is much greater than the old strain. Figure 5. Sweetpotato whitefly adults, nymphs and eggs. The eggs are deposited mainly on the underside of leaves. The eggs are minute, pointed, oblong, and yellow. One female will lay numerous eggs. Near hatching, the apex of the egg will darken. Eggs hatch in 2 to 5 days into crawlers with limited mobility. Crawlers first instar nymphs are yellowish in color and are oval and flattened in appearance.
Once they locate an acceptable feeding site, they become immobile and remain so through four nymphal instars. They feed by inserting their tubular mouthparts into the vein and extracting phloem sap. Late third and fourth instar nymphs have distinctive red eye spots and are termed red-eyed nymphs.
At the end of the fourth instar they enter what is called the pupal stage. Their pupal cases are dome shaped and oval in their outline, and are quite small. Following the pupal stage, fairly mobile adults emerge. As a consequence the size of the whitefly population in a field of fall lettuce is related, in a large part, to the proximity of the crop to cotton or melon fields. Damage: Damage by large whitefly populations can result in crop injury by reducing head size, delaying harvest, and leaf chlorosis associated with whitefly feeding.
Whiteflies also cause economic damage through contamination associated with the insect themselves, honeydew and sooty mold accumulation. Total destruction of early fall lettuce plantings has been observed because whiteflies have extracted large amounts of phloem sap from seedlings. Management and Control: Lettuce planted in high risk situations August and September plantings, or later plantings near a significant whitefly source should be treated prophylactically with a soil-applied systemic insecticide.
Lettuce planted in October, or later when temperatures have declined, should be treated as needed with foliar adulticides. Best control is usually achieved from tank mixing insecticides. Good coverage is essential for adequate control. Lettuce should be monitored as soon as the plants emerge. Whitefly populations will build in cotton and alfalfa, so growers should pay particularly close attention to lettuce planted downwind or adjacent to these fields. Once whitefly adults appear in a field in sufficient numbers, treatments should begin.
Whiteflies are best controlled by preventing colonization; do not allow adults to build and lay eggs. Monitor for whiteflies early in the morning when the adults are sedentary.
Once temperatures begin to increase, the adults will begin to stir and move, and they will become difficult to count. During mid-morning, monitor movement by looking for dispersing swarms. Delaying plantings of fall lettuce until after most cotton has been defoliated and harvested will avoid major whitefly population flights.
Destruction of crops post-harvest is a valuable practice for preventing whitefly population escalation. Once temperatures begin to cool, whiteflies are generally not a problem on lettuce. Thus, spring lettuce is generally not affected by whiteflies. Description and Life History: Liriomyza leafminers occasionally cause economic damage to lettuce. The principal leafminer species in Arizona include L.
Problems with leafminers are most often prevalent in lettuce planted near cotton or melon fields. On lettuce planted in August or September, L. Figure 6. Adult vegetable leafminer fly. The leafminer adults are small, shiny black and yellow flies with a bright yellow triangular spot on the upper thorax between the wings.
Subtle differences in color exist between adult L. The latter species has developed resistance to many insecticides. Females puncture young leaves and oviposit eggs within the leaf. Both male and female flies often feed at puncture sites.
After 2 to 4 days, larvae hatch and begin feeding on plant mesophyll tissue just below the upper surface of the leaf. The winding tunnels that result are initially small and narrow, but increase in size as the larvae grow. After completing three instars in 4 to 20 days, larvae emerge from the mines and drop to the soil to pupate. Pupation takes 7 to 25 days.
On lettuce, leafminers sometimes complete the pupal stage on the plant near the base of the leaf. Adult flies emerge from the pupae after about 7 to 11 days. The entire life cycle can be completed in less than 3 weeks when the temperatures are warm.
Many generations are produced each year in Arizona. Damage: Mining of leaves by the larvae is the principal cause of plant injury. The mines reduce plant photosynthesis, render harvestable portions unmarketable, and provide an access for secondary pathogens. When populations are high, plants may be killed or stressed to the point where pathogens can easily infect the plant. Leafminers can also cause damage after harvest.
Leafminers that cut out of the leaf tissue after harvest will sometimes pupate in-between the leaves. These pupae not only act as contaminates, but will often die and rot, providing a substrate for post-harvest pathogens to infect the lettuce. Management and Control: Monitor young seedlings regularly for the presence of leafminers.
In lettuce, most mines occur on the cotyledons and first true leaves. After thinning, sample leaves from the middle portion of the plant.
If leafminer populations build to high levels when seedlings have only four or five leaves, chemical treatment may be necessary. The threshold for leafminers in lettuce is an average of one or more active mines per leaf except on the marketable portions where damage cannot be tolerated. Sticky traps can assist in determining when early migrations take place, and also help in determining species composition.
It is important to identify the predominant leafminer species, L. Natural enemies, primarily parasitic wasps in the Diglyphus, Opius and Chrysocharis genera, usually maintain leafminer population below economic injury levels. Parasitoids are often killed by insecticides applied to control other pests such as beet armyworm. This results in a secondary outbreak of leafminers. Use of selective insecticides for control of worms will often preserve leafminer parasitoids so that treatment for leafminers will not be necessary.
Description and Life History: Beet armyworm is a key pest of lettuce Fig. In Arizona, it is usually most prevalent from August through November on fall-planted lettuce. However, when temperatures are warm, this pest can be a problem season-long, particularly if alfalfa is nearby. The larvae feed on many field crops, including cotton and alfalfa, and often migrate from these crops onto lettuce in the fall. Several summer annual weeds also serve as hosts.
Eggs are light green in color and are laid in irregular clumps or masses, usually on the under surface of leaves. One female will lay on average to eggs over a 4 to 10 day period. The female moth covers the eggs with white scales from her body, giving the egg masses a cottony appearance. Eggs will darken as they near hatching, and will hatch in 2 to 5 days. The young larvae will feed in groups and spin webs over the underside of the foliage where they are feeding.
Larvae vary in color, but are usually olive green with light-colored stripes down the back and a broader stripe along each side. Beet armyworms usually have a dark spot on the side of the body above the second true leg. Larvae will generally pass through five instars. The armyworm larvae disperse as they get older and move toward the center of the plant.
Large larvae are quite mobile, and a single larva may attack several plants. Larvae reach maturity in about 2 to 3 weeks in warm weather and pupate in the soil. The moth has grayish-brown forewings with a pale spot in the mid-front margin, and the hindwings are white with a dark anterior margin.
Damage: Hatching larvae begin feeding on the leaf and may completely consume seedlings. Beet armyworms may severely stunt or kill seedling lettuce plants.
Damage to lettuce is usually not economically damaging between thinning and cupping stages unless populations are high. However, once cupping begins, larvae may feed on the head, rendering it unmarketable. Armyworm larvae enter heads from the bottom working their way inward while feeding along the leaf margins.
Often the damage cannot be seen without removing frame leaves and dissecting the head. Management and Control: Cultural controls can help suppress armyworm populations. Disk fields immediately following harvest to kill larvae and pupae. Sanitation along field borders is important; armyworms often migrate from weedy field edges into newly planted fields. Monitoring for beet armyworm on lettuce should begin before seedlings emerge.
Control of beet armyworms on seedling lettuce is essential for stand establishment. Check weeds on ditch banks and field borders for larvae and egg masses as fields are being seeded. Once seedlings emerge, sample at least 25 plants in each quadrant of the field twice a week for armyworm egg masses and young larvae. The action threshold for all Lepidopterous larvae in fall lettuce between thinning and heading is one first or second instar larva for every 50 plants.
Many growers have reported difficulty controlling beet armyworms with insecticides, and resistance to Lannate methomyl has been documented in Yuma County. Good spray coverage and insecticide resistance management tactics should be practiced.
Target small larvae which are easier to control with insecticides. Timing insecticide applications at peak egg hatch will improve control. Addition of a B. Just before and after heading, treat if Lepidopterous larvae reach one worm per 25 plants. Description and Life History: The cabbage looper is a very destructive pest on lettuce and will feed on many other crops including cole crops, leafy greens, melons, tomatoes, and cotton Fig.
Cabbage loopers occur year round in Arizona's central and southwestern desert areas. Populations are especially a problem in the fall, when newly-planted winter vegetables are emerging. Figure 8. Cabbage looper larva. Cabbage looper moths lay single, dome-shaped eggs on the under side of older leaves. A single female may lay to eggs.
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