New Mexico Chile Task Force

Growing Season

Pest Management
Irrigation
Cultivation
Fertilization
Pre-Harvest Considerations

Chile Pepper Growers’ Notes : Growing Season (Lay-by to Harvest)

The key to high yield and maximum profit is good management. The following recommendations are key management steps needed to produce a good chile crop. They are based on research findings and the collective experience of the industry's top growers and consultants. Lay-by is considered the last chance to enter the field.

Pest Management

Read the label before using any pesticide. Do not use any chemical, whether it is an herbicide, insecticide, nematicide or fungicide, if it is not labeled for chile (peppers). If you have any question about appropriate product use, consult your County Extension Agent, New Mexico State University (NMSU) specialist, chemical company representative or New Mexico Department of Agriculture (NMDA) Pesticide Division staff (505-646-2133) before using the chemical.

Irrigation and fertilization management and timely cultural practices are important pest management tools.

Insects

Scout/inspect for insects weekly from lay-by through the growing season (up to last harvest). You cannot spend too much time scouting. It needs to be a continual process. Keep aware of insect problems in the immediate area.
Consult with crop adviser or entomology specialist to assess economic threshold. Delay spraying until the economic threshold is reached for a particular insect. This helps in preserving beneficial insects. Repeated applications of foliar insecticides can reduce beneficial insect populations, resulting in secondary pest population increases.
Once the economic threshold for spraying is reached, you must be able to react quickly where treatment is needed.
Insecticide use from lay-by through growing season. Read and follow label directions. If in doubt, contact a crop consultant, NMDA Pesticide Division staff member or NMSU Cooperative Extension Service specialist or agent. Maintaining low pesticide residuals is critical at harvest onset. Pay attention to recommended harvest intervals on label (days between last application and harvest), using pesticides that will leave the lowest residuals. Processor representatives test all fields for pesticide residues. Processors will not accept crops with pesticide residues that are not within tolerance ranges.
Insects of primary concern during this growth stage are:
Insecticides registered in New Mexico that control these insects at this time include:
- Actara. Controls pepper weevils, stinkbugs, aphids, leafminers and beetles.
- Azatin. Controls aphids, armyworms and leafhoppers.
- Warrior with Zeon. Controls aphids, cucumber beetles and leafhoppers.
- Platinum. Controls aphids and whiteflies.
- Triqard. Controls leafminers.
- Confirm. Controls beet armyworms and fall armyworms.
- Spintor. Controls leafminers and beet armyworms.
- Provado. Controls aphids, beet leafhoppers and thrips.
- Fulfill 50WG. Controls aphids and whiteflies.
- Diazinon AG500. Controls aphids and leafminers.
- Thiodan. Controls aphids and leafhoppers.
- Dimethoate 400. Controls aphids and leafminers.
- LBacillus thurengiensis. Biologically controls armyworms.

Diseases
- Biotic diseases that could be present during the growing season include those in the following list. There is no effective chemical control for viral diseases after infection.
- Verticillium wilt. Severe wilting of random plants occurs when pod production starts. The stress of a maturing crop induces the disease's onset. There are no effective measures for controlling verticillium wilt once the disease has occurred in a field. Crop rotation is essential for prevention. Severely infected plants have brown stems and white roots.
- Phytophthora. Infected plants become severely wilted, but leaves remain attached. Symptoms usually don't occur until late summer and early fall. Early season water management aids in control. Excessive soil moisture triggers and intensifies the disease. There must be good drainage so that water is not allowed to stand in fields. Severely infected plants have brown roots and white stems.
- Powdery mildew. This disease favors warm temperatures with high humidity, but can occur at any time throughout the season. The most noticeable sign of the disease is a white, powdery growth on the underside of leaves. Infection can lead to defoliation and production losses. Effective chemical control depends on early disease detection and thorough application coverage, with the fungicide reaching the underside of the leaves and lower plant canopy. The following chemicals show some signs of control for powdery mildew:
- Blossom-end rot. A fruit disorder associated with inconsistent watering and a calcium deficiency (consider the addition of boron (if low soil/plant levels) to increase calcium availability). Root pruning aggravates this disorder.
- Bacterial leaf spot. The bacterial spot pathogens can infect all aboveground parts of the plant. Spots form on leaves, stems and fruit, beginning as small, brown, water-soaked lesions. Warmer temperature, high precipitation and high relative humidity favor disease development. To aid in control, use only Clorox®- (sodium hypochlorite-) treated seed. Bactericides or fungicide-bactericide combinations may be applied where recommended. The following fungicide-bactericides are labeled for use in New Mexcio for bacterial leaf spot control:
- Curly top virus. Peppers of all ages are susceptible to infection but are most susceptible when young. This virus is transmitted by the beet leafhopper. Removal of known weed hosts from crop fields may help to control the disease. Heavy seeding of direct-seeded peppers can compensate somewhat for loss of infected plants.
- Tomato spotted wilt virus. This virus is transmitted from plant to plant almost exclusively by several species of thrips. Thrips must have fed on infected plants as nymphs in order to transmit the virus.
- Abiotic effects during the growing season include:

Weeds (Control weeds in fields and on field edges and ditch banks.)
- The following weeds are of greatest concern in New Mexico chile fields:
- Lay-by applications should have already been applied in properly managed fields. If problems exist that warrant herbicide use be aware of the harvest interval (days) from last application.
- Chemical Control: Read and follow label directions. If in doubt, contact a crop consultant, NMDA Pesticide Division staff member or NMSU Cooperative Extension Service specialist or agent. Note that Treflan‚ and Dual Magnum‚ do not have a lay-by registration. They are only registered for application to chile after thinning. Sandea could be used but needs to be applied as a post-emergence directed treatment.
- Treflan. New Mexico has a Section 24(c) label for a post-emergence incorporated treatment. For control of annual grasses and small-seeded broadleaf weeds, apply to soil surface around 5-7 inch pepper plants and incorporate into the soil after application. Treflan‚ does not control emerged weeds. Destroy existing weeds by cultivation prior to application. (Section 24(c) label must be in the possession of the applicator at the time of application.)
- Dual Magnum. New Mexico has a Section 24(c) label. This chemical is used primarily for the control of yellow nutsedge, annual grasses and select annual broadleaf weeds. It must be applied to freshly tilled, weed-free soil. Dual Magnum‚ will not control established weeds. You must irrigate after application to activate the chemical. (Section 24(c) label must be in the possession of applicator at the time of application.)
- Sandea. This chemical gives good control of both yellow and purple nutsedge. Also, it controls many broadleaf weeds. Apply as a post-emergence directed treatment.
- Poast and Select. These are post-emergence herbicides that target annual grasses and Johnsongrass. The minimum pre-harvest interval, for both, is 20 days after application.

Irrigation

Common Irrigation Scheduling
- Use best water quality source. Sodium adsorption ratio (SAR) of water should be less than 6.
- Optimum irrigation times should be determined by testing soil moisture in the root zone by touch (use soil probe) and with moisture sensors, not by the physical surface appearance of soil and plants. Avoid over-irrigation, which will cause phytophthora and leaching of nutrients out of the root zone.
- Continue to use alternate row irrigation to manage salinity problems. Keep irrigating on the same rows. If water starts to break across the top of beds into un-irrigated rows, open the tail ends of the rows to provide good drainage.
- Irrigation times vary with amount of plant foliage, age, wind, sunlight, rain, temperature fluctuation and relative humidity.
- Water management is the primary control for phytophthora. Good drainage is essential at all times. Phytophthora can develop from water standing in any part of the field at any time. Avoid tailwater (ponding). Monitor weather closely to avoid watering around predicted monsoon rains. During the rainy season, always provide a means to drain fields quickly.
- Water stress, as exemplified by extremes of drying and wetting, increases the incidence of blossom-end rot.
- Jalapeno, green and cayenne irrigation schedules. To ensure a continuous flow of product to the processors, it is important for growers to co-ordinate irrigations around harvest schedules. It is equally important to keep fields at or near field capacity to ensure maximum yields.
- Red chile cut-off date for furrow irrigation is around September 15. The only exception might be unseasonably warm temperatures occurring in late September and early October. This could warrant an additional light watering the last week of September.

Cultivation

By now, cultivation is probably not feasible. Your crop canopy is full or near full and any cultivation would do more harm than good.
Having followed all prior best management practices, including a lay-by herbicide application, weed control practices for this period should be minimal or unnecessary. Address any minimal problems with hand labor. Bindweed and morning glory need control because they will inhibit mechanical harvesting.

Fertilization

During growing season (lay-by to harvest), fertilization needs become dependent on type of harvest (jalapeño, green, cayenne or red).
For jalapeños and green crops. Jalapeños are subject to a multiple harvest (2 to 3 picks). For the most part, green chile is harvested only once, although early harvested green does have potential for a second pick. Jalapeños require nitrogen earlier than green and red chile. They also require more nitrogen at first application in order to achieve plant size. It is important to not let the fertility levels drop in the plant. For this reason you should apply nitrogen during the irrigations immediately prior to and after harvest. This is done to maximize yield and get the plant ready for the next harvest. CAN (Calcium Ammonium Nitrate)-17 should be applied a week prior to green chile harvest to boost yield.
For a cayenne crop, actual fertilizer applications depend on end use and crop potential. If no better data is available, you should follow red crop recommendations for cayenne.
For a red crop, be very careful that you don't over fertilize. Your fertilizer cut-off date for a red crop should be around August 15. This will help to insure adequate maturity at harvest time.
Before full canopy cover test your soil nitrogen (N), phosphorus (P) and potassium (K) levels to see if they are sufficient to get through harvest. You can verify sufficiency best with tissue testing.
Under furrow irrigation, use slow release N (ammonium sulfate) to avoid leaching.
Nutrient management decisions should be based on data from soil testing and leaf petiole analysis. Do not over- or under-fertilize plants.
Consider acid-based liquid fertilizers to improve phosphorus and micronutrient availability.
Micronutrient needs are met best by foliar applications. Time applications based on leaf petiole analysis (sample every 7 days). Some micronutrients can be determined only by tissue testing.
A steady supply of nitrogen is needed during fruit set. Base application rates on data from petiole analysis.
Ammonium nitrogen sources may aggravate blossom-end rot by interfering with calcium uptake.

Tissue Testing (leaf and petiole analyses)

To determine if a crop is adequately nourished, have the plant analyzed during the growing season.

Table 1 shows the recommended range of nutrient levels that should be present in plant tissue. Leaf and petiole analyses will provide you with specific recommendations for your crop. To determine nitrate and phosphate levels, petiole tissue is analyzed. To determine levels of other nutrients, leaf tissue is analyzed.

Table 1. Sufficiency ranges - mid season

Nutrient	Desired Range
Nitrogen (leaf)	35,000-60,000	(3.5 - 5%)
Nitrate (petiole)	>1,000
Phosphorous (leaf)	2,200-7,000	(0.22 - 0.7%)
Phosphate (petiole)	>2,000
Potassium (leaf)	45,000-45,000	(3.5 - 4.5%)
Calcium (leaf)	10,000-25,000	(1 - 2.5%)
Magnesium (leaf)	3,000-10,000	(0.3-1%)
Sulfur (leaf)	3,000-6,000	(0.3-0.6%)
Zinc (leaf)	50-200
Iron (leaf)	60-300
Manganese (leaf)	50-250
Copper (leaf)	6-25
Boron (leaf)	25-75

Pre-Harvest Considerations

Communication. Communication among the grower, company field representative and the processing plant becomes even more critical as the time for harvest nears. Everyone needs to be on the same page about harvest schedules and any problems that have developed. Communication is a must among all parties.
Red Chile Plant Growth Regulator. Any application of a growth regulator should be only by mutual agreement between grower and processor to fit harvesting schedules. If the determination is made that ethephon application is needed to hasten red chile ripening in a particular field, then:
- Apply when about 30% of the fruit are red and about 50% are "mature green." Ethephon will not ripen immature fruit and can reduce yields if applied too early.
- Temperature can greatly affect the activity of ethephon. Use higher concentrations under cool temperature or dense foliage conditions, but lower rates at warmer temperatures.
- Growth regulators should not be applied when temperatures exceed 95o F. (Excessive defoliation and fruit drop can occur.)
- Temperatures below 60o F. reduce or negate the growth regulator's effect.
- Crops receiving ethephon should be harvested within 3-4 weeks of application. Crops scheduled for delayed harvest (after frost) should not receive ethephon treatment.
Defoliant to Aid Harvest. Some growers use sodium chlorate (NaClO3) as a crop desiccant, when crop canopies are thick. Desiccants cause leaves to drop, exposing the pods to more sunlight. Increased light penetration hastens maturity of the pods, helps partially dehydrate the pods and reduces pod diseases caused by slower dry-down and higher humidity under leafy canopies.