After reading the previous post, you already know how to make pumpkins thrive with companion plants. But then you notice some troubling signs. What could be plaguing your precious pumpkins? Don’t fret. This comprehensive guide will walk you through some of the most common pumpkin plant problems, why they happen, and how to fix them. With a few simple tricks, you can get your plants back to peak health just in time for jack-o-lantern season.
Signs of Spoilage
If you notice brown spots or soft mushy areas on your pumpkins, they may be spoiled. This is often caused by bacterial or fungal diseases. Some common culprits are:
- Anthracnose – Causes sunken lesions on leaves, stems, and fruit. Lesions turn orange/brown as they spread. Look for circular spots with rings in the center.
- Bacterial Wilt – Leaves wilt suddenly. Stems ooze smelly slime when cut. Fruit becomes rotten right on the vine.
- Powdery Mildew – White powdery coating on leaves, stems, and fruit. Pumpkins can become misshapen. Leaves may curl up or turn yellow.
- Phytophthora Blight – Causes vines to collapse. Pumpkin skins turn brown or black. Peels easily from fruit.
- Downy Mildew – Yellow patches on upper leaf surfaces. White fuzz on undersides. Vine decline.
To prevent spoilage from disease:
- Allow good airflow between plants to discourage fungi. Avoid overcrowding.
- Water at the base of plants instead of leaves to keep foliage dry.
- Use preventative fungicidal sprays like neem oil early in the season.
- Remove and destroy badly infected plants immediately to prevent spreading.
- Rotate pumpkin crop location yearly to interrupt disease life cycles in soil.
- Monitor soil moisture and avoid excess standing water that breeds pathogens.
If diseases are caught early, you may be able to save infected pumpkins by quickly removing spoiled tissue and treating with a fungicide. But fruits with advanced decay are often unsalvageable and should be discarded.
Lack of Fruit Production
If your pumpkin vines are growing well but you see few female flowers or developing fruit, there are a few possible causes:
- Insufficient pollination – Pumpkins require bee activity and other insect pollinators for transfer of pollen from male to female flowers. Make sure pollinators can access your pumpkins by avoiding pesticide use during bloom time. Consider hand pollination by collecting pollen yourself and brushing it onto female flowers if nature needs a helping hand.
- Poor fruit set – Hot temperatures, dry soil, and other environmental stressors can cause failure of fertilized pumpkin flowers to properly develop into fruit. Keep plants consistently watered 1-2 inches per week and monitor soil nutrients. Provide partial shade cloth if heat spikes during flowering.
- Overcrowding – When pumpkin plants compete too aggressively for sunlight, nutrients, and water, overall fruit production declines. Give each plant ample space and soil resources. For smaller pie pumpkin varieties allow 3 feet between hills. For larger carving types allow up to 8 feet between plants.
- Poor vine health – Various problems like disease, pests, and malnutrition result in reduced flowering and fruit set. Routinely check leaves and vines for signs of issues and treat promptly. Ensure balanced and sufficient nutrition.
- Improper planting time – Pumpkins seeded too late in the season may not transition to flowering and fruiting fast enough before colder fall weather hits. Start seeds or seedlings 4-6 weeks before your average last spring frost date.
- Insufficient light – Pumpkins require at least 8 hours of direct sun for the robust vine growth needed to support fruits. Select a planting site with sun exposure maximized.
Nothing’s more heartbreaking than spotting a rotten pumpkin on the vine before harvest time. Rot usually happens when:
- Fruit sits on consistently wet or moist soil, allowing invasion by bacterial and fungal pathogens. Use mulch around pumpkins and improve drainage if soil remains soggy after watering or rain.
- Vines sustain damage from pests, accidents, or disease, exposing openings to infection. Handle fruits as gently as possible and monitor plants closely for pest issues.
- Hollowed out stems underneath pumpkins can’t supply adequate nutrients. Maintain consistent soil moisture to facilitate vine nutrient transport.
- White spots on fruits signify sunscald, a type of burn. Provide afternoon shade protection if pumpkins are getting sunburned during hottest parts of day.
Once a pumpkin shows signs of rot, quickly remove and discard it. Bury or burn spoiled pumpkins to remove inoculum from the garden. Don’t add diseased fruits to compost piles. For remaining pumpkins, promptly treat affected vines with a fungicide and monitor fruits diligently for further issues.
Seeing your pumpkin plant leaves turn from healthy green to concerning yellow? This chlorosis is most likely due to one of these factors:
- Nitrogen deficiency – Pumpkins are heavy nitrogen feeders. Without sufficient available nitrogen in the soil, leaves can’t manufacture enough chlorophyll and start to yellow. Test soil and supplement with a nitrogen-rich fertilizer as needed per soil test recommendations.
- Root problems – Compacted soil, fungal infections, pests like rootworms or vine borers, and other issues can damage pumpkin roots, limiting their ability to uptake nutrients. Loosen and aerate soil. Rule out soil fungi or root pests.
- Water issues – Both overwatering and underwatering cause nitrogen deficiencies. Too much moisture leaches nitrogen from soil. Too little limits availability. Find the right soil moisture balance.
- Viral diseases – Viruses like cucumber mosaic virus disrupt nutrient flow within the plant, impacting chlorophyll production and causing discoloration. Inspect for other disease signs. Isolate or remove infected plants promptly.
- Insufficient sunlight – Without adequate sunlight, pumpkin leaves can’t complete photosynthesis and produce chlorophyll, leading to yellowing. Ensure plants get at least 8 hours of direct sun, free from shade.
Your pumpkin vines appear stunted, brittle, collapsed, or dead entirely too soon? This vine decline often stems from:
- Frost damage – Exposure to frost or a sudden cold snap causes dieback. Cover plants or use row covers in evening if frost risk. Don’t plant too early when nights remain cold.
- Bacterial wilt – Stems ooze smelly discharge. Vines wilt rapidly. Remove infected plants immediately and do not compost. Sterilize tools after cutting.
- Squash vine borers – White worms bore inside stems and vines, disrupting water and nutrient flow. Cut open vines to remove borers if spotted early.
- Girdling stem – Accidental damage to the base of the plant where vine meets roots interrupts nutrient supply. Bury damaged stems under extra soil to promote new root growth.
- Sudden wilt diseases – Fusarium, verticillium and other fungi cause rapid vine decline. Improve drainage and avoid overwatering which encourages fungal growth.
Act quickly at first signs of vine issues to diagnose the cause and take corrective action if possible. Removing compromised vines rapidly can help reduce disease spread.
Getting Full Size Pumpkins
If your pumpkins seem undersized or aren’t reaching their expected mature size, a few adjustments can help fatten them up:
- Limit each healthy plant to 2-3 fruits for best size. Remove smaller, weaker fruits sets early on.
- Water and fertilize regularly during fruit swell for balanced, sufficient plant nutrition.
- Avoid moving or jostling fruits unnecessarily, which can stunt growth. Handle gently if repositioning is needed.
- Allow fruits to fully ripen on vines until rinds are hard, skins deepest orange, and vines start to die back. Don’t harvest based on size alone.
- Give plants maximum sunlight with at least 8 hours of direct sun daily and ample space between vines for healthy growth.
- Control pest and disease issues which interfere with proper fruit development and maturation.
- For giant pumpkin varieties, use slings to gently support fruits weighing over 25 lbs, taking stress off vines.
- Consider using plant growth regulators like Ethephon to maximize fruit size if going for competition pumpkins.
Let fruits size up on healthy vines as long as possible before first fall frost for biggest pumpkin payoff.
A variety of pests can wreak havoc on pumpkin vines, leaves, and developing fruits if left unchecked:
- Cucumber beetles – Feed on leaves and vines, transmit bacterial wilt. Cover young plants, handpick adults, or use neem oil or pyrethrins.
- Squash bugs – Suck plant juices causing wilt. Remove egg clusters from undersides of leaves. Apply insecticidal soap directly to nymphs.
- Squash vine borers – Clear worms bore into stems. Slit stems lengthwise to remove larvae, bury stem to regrow roots.
- Spider mites – Tiny pests that colonize and feed on undersides of leaves, causing stippling damage. Wash off with water or use insecticidal soap/sulfur.
- Aphids – Clustered soft-bodied insects transmit viruses while sucking juices. Strong sprays of water can treat. Also insecticidal soap, neem oil, or horticultural oils.
- Stink bugs – Feed on fruits causing scarring. Handpick off plants. traps. Remove alternate host weed species.
Closely monitor vines and leaves weekly for signs of pests. Getting infestations under control when limited is critical to avoid major vine and crop damage.
Battling Rodents and Other Vertebrate Pests
Pumpkins aren’t only plagued by insect pests. Larger vertebrate pests can also damage crops:
- Deer – Feed on foliage and young pumpkins. Use fencing around perimeter of garden. Motion-activated sprinklers or lighting can also deter.
- Squirrels – Chew into ripe pumpkins or eat seeds right from the fruit. Use fencing with mesh openings smaller than 1 inch.
- Groundhogs – Feed on vine leaves and fruits. Install underground fencing to block burrows or use humane traps for removal.
- Rabbits – Chew through vines and eat leaves. Protect plants with chicken wire or hardware cloth barriers.
- Raccoons – Carve into ripe pumpkins for the flesh. Electric fencing, noise deterrents, or guard dogs help protect crops.
- Crows – Peck into developing pumpkins for seeds. Scarecrows, owl decoys, or noisemakers may provide relief.
The earlier vertebrate pests are recognized and controlled in the garden, the better the chances of saving pumpkins.
Dealing with Late Season Disease
Downy mildew, powdery mildew, Phytophthora blight, and other pumpkin diseases hit hard late in the growing season right as fruits start maturing. To manage them:
- Improve air circulation and avoid wetting foliage to limit fungal spread. Trellis, prune, or space vines.
- Apply preventative fungicide options like mancozeb, copper, or chlorothalonil starting mid-season before disease appears.
- Remove and discard badly infected plant material immediately to reduce inoculum that can spread spores.
- Source disease-resistant pumpkin varieties when available, like Blue Ballet (powdery mildew tolerance).
- Construct a low tunnel cloche using hoops and row cover fabric to protect plants from spores while allowing sunlight, airflow, and bee access for pollination.
- Inspect fruits, stems and vines daily and harvest pumpkins promptly once ripe to halt disease progression. Discard diseased fruits.
With diligent monitoring and a proactive management approach, you can stay one step ahead of late season pathogens trying to ruin your pumpkin harvest.
Post-Harvest Pumpkin Problems
Your pumpkin woes aren’t necessarily over once fruits are harvested. Proper post-harvest handling is key:
- Cure pumpkins in warm, dry place 10-14 days before carving or display to harden rinds and prevent rotting.
- Disinfect knives and carving tools between pumpkins to avoid introducing pathogens from diseased to healthy fruits.
- Apply antifungal spray after carving to protect exposed inner flesh. Refrigerate carved pumpkins to prolong life.
- Don’t store pumpkins with apples or other ripening fruit which give off ethylene gas, accelerating decay.
- Wash pumpkins gently with mild soap and water, avoiding stems and vines. Don’t immerse fully in water. Dry thoroughly before storing.
- Avoid stacking pumpkins directly atop each other to prevent bruising, splitting, and rot spots.
With proper harvesting techniques and post-harvest care, you can extend the life of prized pumpkins to enjoy through Thanksgiving or beyond!
Still struggling with other perplexing pumpkin problems not covered here? Let me know in the comments! Happy growing.